docs: reflect changes to changelog

BREAKING CHANGE: Consumers must use ESM-compatible environments.
All import paths now include .js extensions.
CommonJS (require) is no longer supported.

CHANGELOG.md

@@ -9,54 +9,148 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- feat: Add new `IdentifierRequiredError` class for missing identifiers.
-- feat: Add the option to use the decorators without passing the identifier: In this case, the identifier will be the class name (register) or the property name (inject).
-- Add pre release building to release workflow on dev/* branches an version changes.
-
 ### Deprecated
 
-
 ### Removed
 
-- feat!: Disable `experimentalDecorators` and `emitDecoratorMetadata` in the `tsconfig.json` file to reflect the change to the stable decorators api.
-
 ### Fixed
 
-- feat!: Update `Register`, `RegisterInstance` and `Inject` decorators to reflect the change to the stable decorators api.
-- feat!: Update `Inject` Decorator typing to reflect the correct property type.
-
 ### Security
 
+## [1.2.0]
+
+### Added
+
+-   docs: added complete Typedoc-style documentation for all `inject()` overloads  
+    Includes parameter descriptions, usage examples, and detailed error annotations for each variant.
+
+## [1.1.0]
+
+### Added
+
+-   feat: exported `inject()` function from the public API via `index.ts`  
+    The function is now available as part of the main module exports.
+
+## [1.0.0]
+
+### Added
+
+-   feat: Enable native ESM support using `"type": "module"` and `moduleResolution: "NodeNext"` in the compiler settings.
+-   feat: All internal imports now explicitly include `.js` extensions for full Node.js ESM compatibility.
+-   feat: Updated `tsconfig.json` to reflect changes for ESM builds (`module: "NodeNext"`, `target: "ES2020"`, etc.).
+-   feat(cli): add `--without-extension` (`-x`) flag to optionally omit file extensions in generated import paths
+-   feat: introduce `inject()` function as a programmatic alternative to the `@Inject` decorator  
+    Supports optional initializers and constructor instantiation for resolved dependencies.  
+    Designed for cases where decorators are not suitable or dynamic resolution is needed.
+-   test: added comprehensive test suite for `inject()` function, covering resolution, initialization, error cases and instantiation behavior
+
+### Changed
+
+-   All source files using relative or internal imports were updated to use `.js` extensions to support Node.js ESM runtime resolution.
+-   test: update Jest config for ts-jest ESM compatibility and .js import support
+-   renamed internal parameter `necessary` → `isNecessary` for naming clarity
+
+### Removed
+
+-   Removed implicit support for CommonJS-style imports without file extensions.
+
+### Deprecated
+
+-   Support for CommonJS consumers using `require()` is no longer available. Use `import` with an ESM-compatible environment instead.
+
+### Fixed
+
+### Security
+
+### ⚠️ Breaking Changes
+
+-   **BREAKING CHANGE**: This version migrates the entire codebase to native ES modules.
+    -   Consumers must use Node.js in ESM mode or compatible bundlers.
+    -   Import paths now include `.js` extensions.
+    -   Using `require()` (CommonJS) to load this library will no longer work.
+    -   All consuming projects must either:
+        -   Use `"type": "module"` in their `package.json`, or
+        -   Use an ESM-aware bundler (e.g. Webpack, Vite, etc.)
+
+## [0.4.0]
+
+### Added
+
+-   feat: Export ImplementsStatic helper function
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+### Security
+
+## [0.3.0]
+
+### Added
+
+-   refactor: consolidate registration decorators
+    Introduced Register decorator to handle class and instance registration in the DI container.
+    Deprecated RegisterInstance in favor of Register, which now internally handles instance registration.
+    Added support for marking dependencies as deprecated with a warning logged upon first resolution.
+    Updated documentation with examples and notes on deprecation.
+-   tests: add mode parameter to RegisterInstanceDecorator
+    Introduced a mode parameter to the test_RegisterInstanceDecorator function allowing 'instance' or 'standalone' modes.
+    Updated test cases to utilize the new mode parameter when registering an instance.
+    Disabled specific ESLint rule in Decorators.test.ts for deprecation warnings.
+    Added an additional test call to test_RegisterInstanceDecorator with 'instance' mode.
+-   refactor: add region tags for overloads in Register.ts
+
+## [0.2.0]
+
+### Added
+
+-   Add pre release building to release workflow on dev/\* branches an version changes.
+-   feat: Introduced a new CLI command `tsinjex-generate` to automate the generation of import statements for registered dependencies.  
+    The command scans `.ts` files for `@Register` and `@RegisterInstance` decorators and generates an `auto-imports.ts` file.  
+    This ensures that all registered dependencies are automatically included without requiring manual imports.  
+    The CLI can be executed via `npx tsinjex-generate` or added as a script in `package.json` for easier integration.
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+### Security
 
 ## [0.0.14]
 
 ### Added
 
-- Added **ChangeLog** file and format it according to [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+-   Added **ChangeLog** file and format it according to [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
-- Added reference to **Semantic Versioning** in the changelog file. (History will be updated on time).
+-   Added reference to **Semantic Versioning** in the changelog file. (History will be updated on time).
-- Version format is now `v0.0.0` instead of `0.0.0`. Changes to this are also reflected in the workflos.
+-   Version format is now `v0.0.0` instead of `0.0.0`. Changes to this are also reflected in the workflos.
-- Add `Identifiers` and `Jest` Sections to the `README.md` file.
+-   Add `Identifiers` and `Jest` Sections to the `README.md` file.
-- feat: Add new Error `InitializationError` to reflect errors during initialization of a dependency.
+-   feat: Add new Error `InitializationError` to reflect errors during initialization of a dependency.
-- feat: Add initialization error handling and refactor Inject.
+-   feat: Add initialization error handling and refactor Inject.
-- feat: After injecting a dependency, the lazzy loading getter will be replaced with the dependency itself.
+-   feat: After injecting a dependency, the lazzy loading getter will be replaced with the dependency itself.
-- feat: remove the use of a private property to store the injected dependencies. Now the dependencies are stored in the property itself.
+-   feat: remove the use of a private property to store the injected dependencies. Now the dependencies are stored in the property itself.
-- test: Add tests for the new features.
+-   test: Add tests for the new features.
-
 
 ### Deprecated
 
-- Deprecated the old version format `0.0.0`.
+-   Deprecated the old version format `0.0.0`.
 
 ### Removed
 
-
 ### Fixed
 
-
 ### Security
 
-
 ---
 
-[unreleased]: https://github.com/PxaMMaxP/TSinjex/compare/0.0.14...HEAD
+[unreleased]: https://github.com/20Max01/TSinjex/compare/v1.0.0...HEAD
-[0.0.14]: https://github.com/PxaMMaxP/TSinjex/compare/0.0.13...v0.0.14
+[1.1.0]: https://github.com/20Max01/TSinjex/compare/v1.1.0...v1.2.0
+[1.1.0]: https://github.com/20Max01/TSinjex/compare/v1.0.0...v1.1.0
+[1.0.0]: https://github.com/20Max01/TSinjex/compare/v0.4.0...v1.0.0
+[0.4.0]: https://github.com/20Max01/TSinjex/compare/v0.3.0...v0.4.0
+[0.3.0]: https://github.com/20Max01/TSinjex/compare/v0.2.0...v0.3.0
+[0.2.0]: https://github.com/20Max01/TSinjex/compare/v0.0.14...v0.2.0
+[0.0.14]: https://github.com/20Max01/TSinjex/compare/v0.0.13...v0.0.14

bin/generate-imports.cjs

@@ -0,0 +1,122 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+const path = require('path');
+const yargs = require('yargs');
+
+// CLI argument parsing
+const argv = yargs
+  .option('src', {
+    alias: 's',
+    type: 'string',
+    description: 'Directory to search for files',
+    default: 'src',
+  })
+  .option('output', {
+    alias: 'o',
+    type: 'string',
+    description: 'Path to the output file',
+    default: 'src/auto-imports.ts',
+  })
+  .option('pattern', {
+    alias: 'p',
+    type: 'string',
+    description: 'File pattern to search for (e.g., .ts, .js)',
+    default: '.ts',
+  })
+  .option('without-extension', {
+    alias: 'x',
+    type: 'boolean',
+    description: 'Omit file extension in import paths',
+    default: false,
+  })
+  .help()
+  .argv;
+
+// Fixed RegEx patterns for decorator detection
+const SEARCH_PATTERNS = [
+  /^@Register(?:<(.+)?>)?\(\s*["']{1}(.+)?["']{1}\s*,?\s*(true|false)?\s*\)/m,
+  /^@RegisterInstance(?:<(.+)?>)?\(\s*["']{1}(.+)?["']{1}\s*,?\s*(.+)?\s*\)/m,
+];
+
+const FILE_PATTERN = argv.pattern.startsWith('.') ? argv.pattern : `.${argv.pattern}`;
+
+/**
+ * Recursively collects all files with a specific extension.
+ * @param {string} dirPath - Root directory
+ * @returns {string[]} List of file paths
+ */
+function getAllFiles(dirPath) {
+  let files = fs.readdirSync(dirPath);
+  let arrayOfFiles = [];
+
+  files.forEach((file) => {
+    const fullPath = path.join(dirPath, file);
+    if (fs.statSync(fullPath).isDirectory()) {
+      arrayOfFiles = arrayOfFiles.concat(getAllFiles(fullPath));
+    } else if (file.endsWith(FILE_PATTERN)) {
+      arrayOfFiles.push(fullPath);
+    }
+  });
+
+  return arrayOfFiles;
+}
+
+/**
+ * Checks files for decorator usage.
+ * @param {string[]} files
+ * @returns {string[]} Filtered files
+ */
+function findFilesWithPattern(files) {
+  return files.filter((file) => {
+    const content = fs.readFileSync(file, 'utf8');
+    return SEARCH_PATTERNS.some((pattern) => pattern.test(content));
+  });
+}
+
+/**
+ * Generates ES-style import statements from file paths.
+ * @param {string[]} files
+ * @returns {string}
+ */
+function generateImports(files) {
+  return files.map((file) => {
+    const relative = './' + path.relative(argv.src, file).replace(/\\/g, '/');
+    const noExt = relative.replace(FILE_PATTERN, '');
+    const finalPath = argv['without-extension'] ? noExt : `${noExt}${FILE_PATTERN}`;
+    return `import '${finalPath}';`;
+  }).join('\n') + '\n';
+}
+
+/**
+ * Script entry point.
+ */
+function main() {
+  try {
+    const srcDir = path.resolve(process.cwd(), argv.src);
+    const outputFile = path.resolve(process.cwd(), argv.output);
+
+    if (!fs.existsSync(srcDir)) {
+      console.error(`❌ Error: The directory '${srcDir}' does not exist.`);
+      process.exit(1);
+    }
+
+    const allFiles = getAllFiles(srcDir);
+    const filesWithPattern = findFilesWithPattern(allFiles);
+
+    if (filesWithPattern.length === 0) {
+      console.log(`ℹ️ No ${FILE_PATTERN} files found matching the specified decorator patterns.`);
+      return;
+    }
+
+    const importContent = generateImports(filesWithPattern);
+    fs.writeFileSync(outputFile, importContent);
+
+    console.log(`✅ Imports successfully generated: ${outputFile}`);
+  } catch (error) {
+    console.error('❌ An error occurred:', error.message);
+    process.exit(1);
+  }
+}
+
+main();

jest.config.cjs

@@ -2,11 +2,17 @@ module.exports = {
     setupFilesAfterEnv: ['./scripts/jest.setup.js'],
     preset: 'ts-jest',
     testEnvironment: 'node',
+    extensionsToTreatAsEsm: ['.ts'],
+    transform: {
+        '^.+\\.ts$': ['ts-jest', { useESM: true }],
+    },
     testMatch: ['**/__tests__/**/*.test.ts', '**/?(*.)+(test).ts'],
     testPathIgnorePatterns: ['\\.spec\\.ts$', '\\.performance\\.test\\.ts$'],
     moduleDirectories: ['node_modules', 'src'],
     moduleNameMapper: {
+        '^src/(.*)\\.js$': '<rootDir>/src/$1',
         '^src/(.*)$': '<rootDir>/src/$1',
+        '^(\\.{1,2}/.*)\\.js$': '$1',
     },
     collectCoverage: true,
     coverageDirectory: '.locale/coverage',

jest.config.coverage.cjs

@@ -1,23 +1,32 @@
 module.exports = {
     setupFilesAfterEnv: ['./scripts/jest.setup.js'],
-    preset: 'ts-jest',
     testEnvironment: 'node',
+    transform: {
+        '^.+\\.ts$': ['ts-jest', { useESM: true }],
+    },
+    extensionsToTreatAsEsm: ['.ts'],
     testMatch: ['**/__tests__/**/*.test.ts', '**/?(*.)+(test).ts'],
     testPathIgnorePatterns: ['\\.spec\\.ts$', '\\.performance\\.test\\.ts$'],
     moduleDirectories: ['node_modules', 'src'],
     moduleNameMapper: {
+        '^src/(.*)\\.js$': '<rootDir>/src/$1',
         '^src/(.*)$': '<rootDir>/src/$1',
+        '^(\\.{1,2}/.*)\\.js$': '$1',
     },
     collectCoverage: true,
     coverageDirectory: '.locale/coverage',
-    coverageReporters: ['text', ['lcov', { projectRoot: '..' }], 'json-summary'],
+    coverageReporters: [
+        'text',
+        ['lcov', { projectRoot: '..' }],
+        'json-summary',
+    ],
     collectCoverageFrom: [
         'src/**/*.{ts,tsx}',
         '!src/**/*.d.ts',
         '!src/**/*.performance.test.ts',
         '!src/**/*.spec.ts',
         '!src/**/*.test.ts',
-        '!src/auto-imports.ts'
+        '!src/auto-imports.ts',
     ],
     coverageThreshold: {
         global: {

package-lock.json

@@ -1,17 +1,20 @@
 {
   "name": "ts-injex",
-  "version": "0.1.0-alpha",
+  "version": "1.0.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "ts-injex",
-      "version": "0.1.0-alpha",
+      "version": "1.0.0",
       "license": "MIT",
       "dependencies": {
         "eslint-plugin-prettier": "^5.2.1",
         "jest-environment-jsdom": "^29.7.0"
       },
+      "bin": {
+        "tsinjex-generate": "bin/generate-imports.cjs"
+      },
       "devDependencies": {
         "@stylistic/eslint-plugin": "^2.6.2",
         "@types/jest": "^29.5.12",
@@ -5958,11 +5961,6 @@
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-18.3.1.tgz",
       "integrity": "sha512-/LLMVyas0ljjAtoYiPqYiL8VWXzUUdThrmU5+n20DZv+a+ClRoevUzw5JxU+Ieh5/c87ytoTBV9G1FiKfNJdmg=="
     },
-    "node_modules/reflect-metadata": {
-      "version": "0.2.2",
-      "resolved": "https://registry.npmjs.org/reflect-metadata/-/reflect-metadata-0.2.2.tgz",
-      "integrity": "sha512-urBwgfrvVP/eAyXx4hluJivBKzuEbSQs9rKWCrCkbSxNv8mxPcUZKeuoF3Uy4mJl3Lwprp6yy5/39VWigZ4K6Q=="
-    },
     "node_modules/regexp.prototype.flags": {
       "version": "1.5.2",
       "resolved": "https://registry.npmjs.org/regexp.prototype.flags/-/regexp.prototype.flags-1.5.2.tgz",

package.json

@@ -1,10 +1,13 @@
 {
   "name": "ts-injex",
-  "version": "0.1.0-alpha",
+  "version": "1.2.0",
   "description": "Simple boilerplate code free dependency injection system for TypeScript.",
   "type": "module",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
+  "bin": {
+    "tsinjex-generate": "./bin/generate-imports.cjs"
+  },
   "scripts": {
     "prepare": "npm run build",
     "build": "npm run build:tsc",

src/__tests__/Decorators.spec.ts

@@ -1,9 +1,9 @@
 /* istanbul ignore file */
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import { Inject } from 'src/decorators/Inject';
+import { Inject } from '../decorators/Inject.js';
-import { DependencyResolutionError } from '../interfaces/Exceptions';
+import { DependencyResolutionError } from '../interfaces/Exceptions.js';
-import { ITSinjex_, ITSinjex } from '../interfaces/ITSinjex';
+import { ITSinjex_, ITSinjex } from '../interfaces/ITSinjex.js';
-import { ForceConstructor } from '../types/GenericContructor';
+import { ForceConstructor } from '../types/GenericContructor.js';
 
 /**
  * Test the Inject decorator.
@@ -67,29 +67,6 @@ export function test_InjectDecorator(
             expect(instance.getDependency().value).toBe('test-value-init');
         });
 
-        it('should inject dependency and run initializer without identifier', () => {
-            container.register('MockDependencyIdentifier', {
-                value: 'test-value',
-            });
-
-            class TestClass {
-                @Inject(undefined, (x: string) => {
-                    (x as unknown as { value: string }).value =
-                        'test-value-init';
-
-                    return x;
-                })
-                MockDependencyIdentifier!: any;
-
-                public getDependency() {
-                    return this.MockDependencyIdentifier;
-                }
-            }
-
-            const instance = new TestClass();
-            expect(instance.getDependency().value).toBe('test-value-init');
-        });
-
         it('should throw an error when necessary is true and the initializer throws an error', () => {
             let _error: Error | undefined = undefined;
 
@@ -101,7 +78,7 @@ export function test_InjectDecorator(
                 class TestClass {
                     @Inject(
                         'InitThrowDependencie',
-                        (): any => {
+                        () => {
                             throw new Error('Initializer error');
                         },
                         true,
@@ -298,19 +275,6 @@ export function test_RegisterDecorator(
                 TestClass,
             );
         });
-
-        it('should register a dependency without an identifier', () => {
-            @register()
-            class TestClass {
-                private readonly _dependency!: any;
-
-                public getDependency() {
-                    return this._dependency;
-                }
-            }
-
-            expect(container.resolve('TestClass')).toBe(TestClass);
-        });
     });
 }
 
@@ -318,6 +282,7 @@ export function test_RegisterInstanceDecorator(
     Container: ITSinjex_,
     // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
     registerInstance: Function,
+    mode: 'instance' | 'standalone' = 'standalone',
 ): void {
     describe('RegisterInstance Decorator Tests', () => {
         let container: ITSinjex;
@@ -331,7 +296,10 @@ export function test_RegisterInstanceDecorator(
         });
 
         it('should register an instance of a dependency', () => {
-            @registerInstance('InstanceIdentifier')
+            @registerInstance(
+                'InstanceIdentifier',
+                mode === 'instance' ? 'instance' : undefined,
+            )
             class TestClass {
                 private readonly _dependency!: any;
 
@@ -347,23 +315,6 @@ export function test_RegisterInstanceDecorator(
             ).toBe('instance');
         });
 
-        it('should register an instance of a dependency with an identifier', () => {
-            @registerInstance()
-            class TestClass {
-                private readonly _dependency!: any;
-
-                public getDependency() {
-                    return this._dependency;
-                }
-
-                public mark: string = 'instance';
-            }
-
-            expect(container.resolve<TestClass>('TestClass').mark).toBe(
-                'instance',
-            );
-        });
-
         it('should register an instance of a dependency an run the init function', () => {
             @registerInstance(
                 'InstanceIdentifier',
@@ -390,7 +341,10 @@ export function test_RegisterInstanceDecorator(
         });
 
         it('should register an instance of a dependency and get it on set', () => {
-            @registerInstance('InstanceIdentifier')
+            @registerInstance(
+                'InstanceIdentifier',
+                mode === 'instance' ? 'instance' : undefined,
+            )
             class TestClass {
                 private readonly _dependency!: any;
 

src/__tests__/Decorators.test.ts

@@ -1,15 +1,18 @@
-import { TSinjex } from 'src/classes/TSinjex';
+/* eslint-disable deprecation/deprecation */
-import { Inject } from 'src/decorators/Inject';
+import { TSinjex } from 'src/classes/TSinjex.js';
-import { Register } from 'src/decorators/Register';
+import { Inject } from 'src/decorators/Inject.js';
-import { RegisterInstance } from 'src/decorators/RegisterInstance';
+import { Register } from 'src/decorators/Register.js';
+import { RegisterInstance } from 'src/decorators/RegisterInstance.js';
 import {
     test_InjectDecorator,
     test_RegisterDecorator,
     test_RegisterInstanceDecorator,
-} from './Decorators.spec';
+} from './Decorators.spec.js';
 
 test_InjectDecorator(TSinjex, Inject);
 
 test_RegisterDecorator(TSinjex, Register);
 
 test_RegisterInstanceDecorator(TSinjex, RegisterInstance);
+
+test_RegisterInstanceDecorator(TSinjex, Register, 'instance');

src/__tests__/Functions.spec.ts

@@ -1,6 +1,11 @@
 /* istanbul ignore file */
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import { ITSinjex, ITSinjex_ } from 'src/interfaces/ITSinjex';
+import {
+    DependencyResolutionError,
+    InitializationError,
+    NoInstantiationMethodError,
+} from '../interfaces/Exceptions.js';
+import { ITSinjex, ITSinjex_ } from '../interfaces/ITSinjex.js';
 
 export function test_RegisterFunction(
     Container: ITSinjex_,
@@ -69,3 +74,111 @@ export function test_ResolveFunction(
         });
     });
 }
+
+/**
+ * Test the inject function.
+ * @param Container The DI container implementation to test against.
+ * @param inject The inject function to test.
+ */
+export function test_injectFunction(
+    Container: ITSinjex_,
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
+    inject: Function,
+): void {
+    describe('inject Function Tests', () => {
+        let container: ITSinjex;
+
+        beforeEach(() => {
+            // Reset singleton
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+            (Container as any)['_instance'] = undefined;
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+            (Container as any)['_dependencies'] = undefined;
+            container = Container.getInstance();
+        });
+
+        it('should resolve and return the dependency as is', () => {
+            container.register('SimpleDep', { value: 'test' });
+
+            const resolved = inject('SimpleDep');
+            expect(resolved.value).toBe('test');
+        });
+
+        it('should resolve and run the initializer function', () => {
+            container.register('DepWithInit', { value: 'before' });
+
+            const resolved = inject('DepWithInit', (dep: any) => {
+                dep.value = 'after';
+
+                return dep;
+            });
+
+            expect(resolved.value).toBe('after');
+        });
+
+        it('should resolve and instantiate the dependency if init is true and constructor exists', () => {
+            class WithConstructor {
+                value = 'constructed';
+            }
+
+            container.register('Constructable', WithConstructor);
+
+            const resolved = inject('Constructable', true);
+            expect(resolved.value).toBe('constructed');
+        });
+
+        it('should return undefined if dependency is not found and not necessary', () => {
+            const resolved = inject('NonExistentDep', undefined, false);
+            expect(resolved).toBeUndefined();
+        });
+
+        it('should throw DependencyResolutionError if dependency is not found and necessary', () => {
+            expect(() => inject('MissingDep')).toThrow(
+                DependencyResolutionError,
+            );
+        });
+
+        it('should throw InitializationError if init function throws', () => {
+            container.register('InitThrows', {});
+
+            expect(() =>
+                inject('InitThrows', () => {
+                    throw new Error('fail');
+                }),
+            ).toThrow(InitializationError);
+        });
+
+        it('should throw NoInstantiationMethodError if init = true and no constructor exists', () => {
+            container.register('NonConstructable', {});
+
+            expect(() => inject('NonConstructable', true)).toThrow(
+                NoInstantiationMethodError,
+            );
+        });
+
+        it('should not throw if no constructor and necessary = false', () => {
+            container.register('SafeSkip', {});
+            expect(() => inject('SafeSkip', true, false)).not.toThrow();
+        });
+
+        it('should return undefined if initializer fails and not necessary', () => {
+            container.register('InitErrorOptional', {});
+
+            const result = inject(
+                'InitErrorOptional',
+                () => {
+                    throw new Error('ignored');
+                },
+                false,
+            );
+
+            expect(result).toBeUndefined();
+        });
+
+        it('should return undefined if dependency is null and not necessary', () => {
+            container.register('NullDep', null);
+            const result = inject('NullDep', true, false);
+            expect(result).toBeUndefined();
+        });
+    });
+}

src/__tests__/Functions.test.ts

@@ -1,7 +1,13 @@
-import { TSinjex } from 'src/classes/TSinjex';
+import {
-import { register } from 'src/functions/register';
+    test_injectFunction,
-import { resolve } from 'src/functions/resolve';
+    test_RegisterFunction,
-import { test_RegisterFunction, test_ResolveFunction } from './Functions.spec';
+    test_ResolveFunction,
+} from './Functions.spec.js';
+import { TSinjex } from '../classes/TSinjex.js';
+import { inject } from '../functions/inject.js';
+import { register } from '../functions/register.js';
+import { resolve } from '../functions/resolve.js';
 
 test_RegisterFunction(TSinjex, register);
 test_ResolveFunction(TSinjex, resolve);
+test_injectFunction(TSinjex, inject);

src/__tests__/ITSinjex.spec.ts

@@ -1,5 +1,5 @@
 /* istanbul ignore file */
-import { ITSinjex_, ITSinjex } from '../interfaces/ITSinjex';
+import { ITSinjex_, ITSinjex } from '../interfaces/ITSinjex.js';
 
 /**
  * Test the implementation of the `ITSinjex` interface.

src/__tests__/TSinjex.test.ts

@@ -1,4 +1,4 @@
-import { test_ITSinjex } from './ITSinjex.spec';
+import { test_ITSinjex } from './ITSinjex.spec.js';
-import { TSinjex } from '../classes/TSinjex';
+import { TSinjex } from '../classes/TSinjex.js';
 
 test_ITSinjex(TSinjex);

src/classes/TSinjex.ts

@@ -1,13 +1,13 @@
-import type { Inject } from '../decorators/Inject';
+import type { Inject } from '../decorators/Inject.js';
-import type { Register } from '../decorators/Register';
+import type { Register } from '../decorators/Register.js';
-import type { RegisterInstance } from '../decorators/RegisterInstance';
+import type { RegisterInstance } from '../decorators/RegisterInstance.js';
-import type { register } from '../functions/register';
+import type { register } from '../functions/register.js';
-import type { resolve } from '../functions/resolve';
+import type { resolve } from '../functions/resolve.js';
-import { ImplementsStatic } from '../helper/ImplementsStatic';
+import { ImplementsStatic } from '../helper/ImplementsStatic.js';
-import { DependencyResolutionError } from '../interfaces/Exceptions';
+import { DependencyResolutionError } from '../interfaces/Exceptions.js';
-import { IDependency } from '../interfaces/IDependency';
+import { IDependency } from '../interfaces/IDependency.js';
-import { ITSinjex, ITSinjex_ } from '../interfaces/ITSinjex';
+import { ITSinjex, ITSinjex_ } from '../interfaces/ITSinjex.js';
-import { Identifier } from '../types/Identifier';
+import { Identifier } from '../types/Identifier.js';
 
 /**
  * # TSinjex

src/decorators/Inject.ts

@@ -1,27 +1,26 @@
-import { TSinjex } from '../classes/TSinjex';
+import { TSinjex } from '../classes/TSinjex.js';
 import {
     DependencyResolutionError,
-    IdentifierRequiredError,
     InitializationError,
     InjectorError,
     NoInstantiationMethodError,
-} from '../interfaces/Exceptions';
+} from '../interfaces/Exceptions.js';
-import { Identifier } from '../types/Identifier';
+import { Identifier } from '../types/Identifier.js';
-import { InitDelegate } from '../types/InitDelegate';
+import { InitDelegate } from '../types/InitDelegate.js';
 
 /**
  * A decorator to inject a dependency from a DI (Dependency Injection) container into a class property.
- * @template TargetType The type of the class to inject the dependency into.
+ * @template T The type of the dependency to be injected.
- * @template DependencyType The type of the dependency to be injected.
+ * @template U The type of the property to be injected.
- * @template PropertyType The type of the property to be injected.
+ * @param identifier The identifier used to resolve the class in the DI container.
- * @param identifier The {@link Identifier|identifier} used to resolve the dependencie in the DI container or the property name if not provided.
+ * @see {@link Identifier} for more information on identifiers.
- * @param init An optional initializer {@link InitDelegate|function} to transform the dependency before injection
+ * @param init Optional an initializer function to transform the dependency before injection
  * or true to instantiate the dependency if it has a constructor.
- * @param necessary If true, throws an error if the dependency is not found.
+ * @see {@link InitDelegate} for more information on initializer functions.
+ * @param isNecessary If true, throws an error if the dependency is not found.
  * @returns The resolved dependency or undefined if the dependency is not necessary
  * and not found, or throws an error if the dependency is necessary and not found.
  * @throws **Only throws errors if the dependency is necessary.**
- * @throws An {@link IdentifierRequiredError} if the identifier is not provided and the class name is not available.
  * @throws A {@link DependencyResolutionError} if the dependency is not found.
  * @throws A {@link InjectorError} if an error occurs during the injection process.
  * @throws A {@link NoInstantiationMethodError} if the dependency does not have a constructor.
@@ -41,83 +40,71 @@ import { InitDelegate } from '../types/InitDelegate';
  * }
  * ```
  */
-export function Inject<TargetType, DependencyType, PropertyType>(
+export function Inject<T, U>(
-    identifier?: Identifier,
+    identifier: Identifier,
-    init?: InitDelegate<DependencyType, PropertyType> | true,
+    init?: InitDelegate<T, U> | true,
-    necessary = true,
+    isNecessary = true,
 ) {
-    return function (
+    return function (target: unknown, propertyKey: string | symbol): void {
-        constructor: undefined,
-        context: ClassFieldDecoratorContext<TargetType>,
-    ): (
-        this: TargetType,
-        initialValue: PropertyType | undefined,
-    ) => PropertyType {
-        const _identifier = identifier ?? context.name;
-
-        if (_identifier == null && necessary === true)
-            throw new IdentifierRequiredError();
-
         /**
          * Function to evaluate the dependency lazily
          * to avoid circular dependencies, not found dependencies, etc.
          * @returns The resolved dependency or undefined if the dependency is not found.
          */
-        const resolve = (): DependencyType | undefined => {
+        const resolve = (): T | undefined => {
-            return TSinjex.getInstance().resolve<DependencyType>(
+            return TSinjex.getInstance().resolve<T>(identifier, isNecessary);
-                _identifier,
-                necessary,
-            );
         };
 
-        return function (
+        Object.defineProperty(target, propertyKey, {
-            this: TargetType,
+            get() {
-            initialValue: PropertyType | undefined,
+                let instance: T | U | undefined;
-        ): PropertyType {
-            let instance: DependencyType | PropertyType | undefined;
 
-            const dependency: DependencyType | undefined = tryAndCatch(
+                const dependency: T | undefined = tryAndCatch(
-                () => resolve(),
+                    () => resolve(),
-                necessary,
+                    isNecessary,
-                _identifier,
+                    identifier,
-                DependencyResolutionError,
+                    DependencyResolutionError,
-            );
+                );
 
-            if (dependency != null) {
+                if (dependency != null) {
-                const initFunction: (() => PropertyType) | undefined =
+                    const initFunction: (() => U) | undefined =
-                    typeof init === 'function' && dependency != null
+                        typeof init === 'function' && dependency != null
-                        ? (): PropertyType => init(dependency)
+                            ? (): U => init(dependency)
-                        : init === true && hasConstructor(dependency)
+                            : init === true && hasConstructor(dependency)
-                          ? (): PropertyType => new dependency() as PropertyType
+                              ? (): U => new dependency() as U
-                          : undefined;
+                              : undefined;
 
-                if (init == null) instance = dependency;
+                    if (init == null) instance = dependency;
-                else if (initFunction != null)
+                    else if (initFunction != null)
-                    instance = tryAndCatch(
+                        instance = tryAndCatch(
-                        initFunction,
+                            initFunction,
-                        necessary,
+                            isNecessary,
-                        _identifier,
+                            identifier,
-                        InitializationError,
+                            InitializationError,
-                    );
+                        );
-                else if (necessary)
+                    else if (isNecessary)
-                    throw new NoInstantiationMethodError(_identifier);
+                        throw new NoInstantiationMethodError(identifier);
-            } else if (necessary)
+                } else if (isNecessary)
-                throw new DependencyResolutionError(_identifier);
+                    throw new DependencyResolutionError(identifier);
 
+                /**
+                 * Replace itself with the resolved dependency
+                 * for performance reasons.
+                 */
+                Object.defineProperty(this, propertyKey, {
+                    value: instance,
+                    writable: false,
+                    enumerable: false,
+                    configurable: false,
+                });
+
+                return instance;
+            },
             /**
-             * Replace itself with the resolved dependency
+             * Make the property configurable to allow replacing it
-             * for performance reasons.
              */
-            Object.defineProperty(this, context.name, {
+            configurable: true,
-                value: instance,
+        });
-                writable: false,
-                enumerable: false,
-                configurable: false,
-            });
-
-            // eslint-disable-next-line @typescript-eslint/no-explicit-any
-            return instance as any;
-        };
     };
 }
 

src/decorators/Register.ts

@@ -1,14 +1,142 @@
-import { TSinjex } from '../classes/TSinjex';
+import { InitDelegate } from 'src/types/InitDelegate.js';
-import { IdentifierRequiredError } from '../interfaces/Exceptions';
+import { TSinjex } from '../classes/TSinjex.js';
-import { Identifier } from '../types/Identifier';
+import { Identifier } from '../types/Identifier.js';
+
+//#region Overloads
 
 /**
  * A decorator to register a class in the **TSinjex** DI (Dependency Injection) container.
  * @template TargetType The type of the class to be registered.
- * @param identifier The {@link Identifier|identifier} used to register the class in the DI container or the class name if not provided.
+ * @param identifier The identifier used to register the class in the DI container.
- * @param deprecated If true, the dependency is deprecated and a warning is logged only once upon the first resolution of the dependency.
+ * @see {@link Identifier} for more information on identifiers.
+ * @param deprecated If true, the dependency is deprecated and a warning
+ * is logged only once upon the first resolution of the dependency.
+ * @returns The decorator function to be applied on the class.
+ * @example
+ * ```ts
+ * \@Register('MyClassIdentifier')
+ * class MyClass {
+ *   // ...
+ * }
+ * ```
+ * @example
+ * ```ts
+ * \@Register('MyClassIdentifier', true)
+ * class MyClass {
+ *   // ...
+ * }
+ * ```
+ */
+export function Register<
+    TargetType extends new (...args: unknown[]) => InstanceType<TargetType>,
+>(
+    identifier: Identifier,
+    deprecated?: boolean,
+): (constructor: TargetType, ...args: unknown[]) => void;
+
+/**
+ * A decorator to register an instance of a class in the DI (Dependency Injection) container.
+ * @template TargetType The type of the class whose instance is to be registered.
+ * @param identifier The identifier used to register the instance in the DI container.
+ * @see {@link Identifier} for more information on identifiers.
+ * @param shouldRegister Set to 'instance' to register the instance in the DI container
+ * with an empty constructor.
+ * @param deprecated If true, the dependency is deprecated and a warning
+ * is logged only once upon the first resolution of the dependency.
+ * @returns The decorator function to be applied on the class.
+ * @example
+ * ```ts
+ * \@RegisterInstance('MyClassInstanceIdentifier', 'instance')
+ * class MyClass {
+ *   // ...
+ * }
+ * ```
+ * @example
+ * ```ts
+ * \@RegisterInstance('MyClassInstanceIdentifier', 'instance', true)
+ * class MyClass {
+ *   // ...
+ * }
+ * ```
+ */
+export function Register<
+    TargetType extends new (..._args: unknown[]) => InstanceType<TargetType>,
+>(
+    identifier: Identifier,
+    shouldRegister: 'instance',
+    deprecated?: boolean,
+): (constructor: TargetType, ...args: unknown[]) => void;
+
+/**
+ * A decorator to register an instance of a class in the DI (Dependency Injection) container.
+ * @template TargetType The type of the class whose instance is to be registered.
+ * @param identifier The identifier used to register the instance in the DI container.
+ * @see {@link Identifier} for more information on identifiers.
+ * @param init An optional initializer function which get the constructor of the class
+ * as input and returns an instance of the class.
+ * @param deprecated If true, the dependency is deprecated and a warning
+ * is logged only once upon the first resolution of the dependency.
+ * @see {@link InitDelegate} for more information on initializer functions.
+ * @returns The decorator function to be applied on the class.
+ * @example
+ * ```ts
+ * \@RegisterInstance('MyClassInstanceIdentifier', (constructor) => new constructor())
+ * class MyClass {
+ *   // ...
+ * }
+ * ```
+ * @example
+ * ```ts
+ * \@RegisterInstance('MyClassInstanceIdentifier', (constructor) => new constructor(), true)
+ * class MyClass {
+ *   // ...
+ * }
+ * ```
+ */
+export function Register<
+    TargetType extends new (..._args: unknown[]) => InstanceType<TargetType>,
+>(
+    identifier: Identifier,
+    init?: InitDelegate<
+        TargetType & { new (..._args: unknown[]): InstanceType<TargetType> },
+        InstanceType<TargetType>
+    >,
+    deprecated?: boolean,
+): (constructor: TargetType, ...args: unknown[]) => void;
+
+//#endregion Overloads
+
+// eslint-disable-next-line jsdoc/require-jsdoc
+export function Register<
+    TargetType extends new (...args: unknown[]) => InstanceType<TargetType>,
+>(
+    identifier: Identifier,
+    arg1?:
+        | undefined
+        | boolean
+        | InitDelegate<TargetType, InstanceType<TargetType>>
+        | 'instance',
+    arg2?: boolean,
+): (constructor: TargetType, ...args: unknown[]) => void {
+    const deprecated = typeof arg1 === 'boolean' ? arg1 : arg2;
+    const init = typeof arg1 === 'function' ? arg1 : undefined;
+    const shouldRegisterInstance = arg1 === 'instance';
+
+    if (init == undefined && shouldRegisterInstance !== true) {
+        return _register(identifier, deprecated);
+    } else {
+        return _registerInstance(identifier, init, deprecated);
+    }
+}
+
+/**
+ * A decorator to register a class in the **TSinjex** DI (Dependency Injection) container.
+ * @template TargetType The type of the class to be registered.
+ * @param identifier The identifier used to register the class in the DI container.
+ * @see {@link Identifier} for more information on identifiers.
+ * @param deprecated If true, the dependency is deprecated and a warning
+ * is logged only once upon the first resolution of the dependency.
  * @returns The decorator function to be applied on the class.
- * @throws An {@link IdentifierRequiredError} if the identifier is not provided and the class name is not available.
  * @example
  * ```ts
  * \@Register('MyClassIdentifier')
@@ -17,18 +145,122 @@ import { Identifier } from '../types/Identifier';
  * }
  * ```
  */
-export function Register<
+function _register<
     TargetType extends new (...args: unknown[]) => InstanceType<TargetType>,
->(identifier?: Identifier, deprecated?: boolean) {
+>(identifier: Identifier, deprecated?: boolean) {
-    return function (
+    return function (constructor: TargetType, ...args: unknown[]): void {
-        constructor: TargetType,
+        // Get the instance of the DI container
-        context: ClassDecoratorContext<TargetType>,
-    ) {
-        const _identifier = identifier ?? context.name;
-
-        if (_identifier == null) throw new IdentifierRequiredError();
-
         const diContainer = TSinjex.getInstance();
-        diContainer.register(_identifier, constructor, deprecated);
+
+        // Register the class in the DI container
+        diContainer.register(identifier, constructor, deprecated);
     };
 }
+
+/**
+ * A decorator to register an instance of a class in the DI (Dependency Injection) container.
+ * @template TargetType The type of the class whose instance is to be registered.
+ * @param identifier The identifier used to register the instance in the DI container.
+ * @see {@link Identifier} for more information on identifiers.
+ * @param init An optional initializer function which get the constructor of the class
+ * as input and returns an instance of the class.
+ * @param deprecated If true, the dependency is deprecated and a warning
+ * is logged only once upon the first resolution of the dependency.
+ * @see {@link InitDelegate} for more information on initializer functions.
+ * @returns The decorator function to be applied on the class.
+ * @example
+ * ```ts
+ * \@RegisterInstance('MyClassInstanceIdentifier', (constructor) => new constructor())
+ * class MyClass {
+ *   // ...
+ * }
+ * ```
+ */
+function _registerInstance<
+    TargetType extends new (..._args: unknown[]) => InstanceType<TargetType>,
+>(
+    identifier: Identifier,
+    init?: InitDelegate<
+        TargetType & { new (..._args: unknown[]): InstanceType<TargetType> },
+        InstanceType<TargetType>
+    >,
+    deprecated?: boolean,
+) {
+    return function (constructor: TargetType, ...args: unknown[]): void {
+        // Get the instance of the DI container
+        const diContainer = TSinjex.getInstance();
+        let instance: InstanceType<TargetType>;
+
+        // Create a proxy to instantiate the class when needed (Lazy Initialization)
+        let lazyProxy: unknown = new Proxy(
+            {},
+            {
+                get(target, prop, receiver) {
+                    ({ instance, lazyProxy } = initializeInstance<TargetType>(
+                        instance,
+                        init,
+                        constructor,
+                        args,
+                        lazyProxy,
+                    ));
+
+                    // Return the requested property of the instance
+                    return instance[prop as keyof InstanceType<TargetType>];
+                },
+                set(target, prop, value, receiver) {
+                    ({ instance, lazyProxy } = initializeInstance<TargetType>(
+                        instance,
+                        init,
+                        constructor,
+                        args,
+                        lazyProxy,
+                    ));
+
+                    // Set the requested property of the instance
+                    return (instance[prop as keyof InstanceType<TargetType>] =
+                        value);
+                },
+            },
+        );
+
+        // Register the lazy proxy in the DI container
+        diContainer.register(identifier, lazyProxy, deprecated);
+    };
+}
+
+/**
+ * Initializes the instance of the class.
+ * @template TargetType The type of the class whose instance is to be initialized.
+ * @param instance The instance of the class to be initialized.
+ * @param init The optional initializer function to initialize the instance.
+ * @param constructor The constructor of the class.
+ * @param args The arguments to be passed to the constructor of the class.
+ * @param lazyProxy The lazy proxy to instantiate the class when needed.
+ * @returns The initialized instance and the lazy proxy.
+ */
+function initializeInstance<
+    TargetType extends new (..._args: unknown[]) => InstanceType<TargetType>,
+>(
+    instance: InstanceType<TargetType>,
+    init:
+        | InitDelegate<
+              TargetType &
+                  (new (..._args: unknown[]) => InstanceType<TargetType>),
+              InstanceType<TargetType>
+          >
+        | undefined,
+    constructor: TargetType,
+    args: unknown[],
+    lazyProxy: unknown,
+): { instance: InstanceType<TargetType>; lazyProxy: unknown } {
+    if (instance == null) {
+        if (init) {
+            instance = init(constructor);
+        } else {
+            instance = new constructor(...args);
+        }
+    }
+    lazyProxy = instance;
+
+    return { instance, lazyProxy };
+}

src/decorators/RegisterInstance.ts

@@ -1,16 +1,18 @@
-import { TSinjex } from '../classes/TSinjex';
+import { Register } from './Register.js';
-import { IdentifierRequiredError } from '../interfaces/Exceptions';
+import { Identifier } from '../types/Identifier.js';
-import { Identifier } from '../types/Identifier';
+import { InitDelegate } from '../types/InitDelegate.js';
-import { InitDelegate } from '../types/InitDelegate';
 
 /**
  * A decorator to register an instance of a class in the DI (Dependency Injection) container.
  * @template TargetType The type of the class whose instance is to be registered.
- * @param identifier The {@link Identifier|identifier} used to register the class in the DI container or the class name if not provided.
+ * @param identifier The identifier used to register the instance in the DI container.
- * @param init An optional initializer {@link InitDelegate|function} which get the constructor of the class
+ * @see {@link Identifier} for more information on identifiers.
+ * @param init An optional initializer function which get the constructor of the class
  * as input and returns an instance of the class.
+ * @param deprecated If true, the dependency is deprecated and a warning
+ * is logged only once upon the first resolution of the dependency.
+ * @see {@link InitDelegate} for more information on initializer functions.
  * @returns The decorator function to be applied on the class.
- * @throws An {@link IdentifierRequiredError} if the identifier is not provided and the class name is not available.
  * @example
  * ```ts
  * \@RegisterInstance('MyClassInstanceIdentifier', (constructor) => new constructor())
@@ -18,63 +20,20 @@ import { InitDelegate } from '../types/InitDelegate';
  *   // ...
  * }
  * ```
+ * @deprecated Use {@link Register} instead. This decorator already uses the {@link Register} decorator internally.
  */
 export function RegisterInstance<
     TargetType extends new (..._args: unknown[]) => InstanceType<TargetType>,
 >(
-    identifier?: Identifier,
+    identifier: Identifier,
     init?: InitDelegate<
         TargetType & { new (..._args: unknown[]): InstanceType<TargetType> },
         InstanceType<TargetType>
     >,
-) {
+    deprecated?: boolean,
-    return function (
+): (constructor: TargetType, ...args: unknown[]) => void {
-        constructor: TargetType,
+    const initDelegate = typeof init === 'function' ? init : undefined;
-        context: ClassDecoratorContext<TargetType>,
-    ): void {
-        const _identifier = identifier ?? context.name;
 
-        if (_identifier == null) throw new IdentifierRequiredError();
+    if (initDelegate) return Register(identifier, initDelegate, deprecated);
-
+    else return Register(identifier, 'instance', deprecated);
-        const diContainer = TSinjex.getInstance();
-        let instance: InstanceType<TargetType>;
-
-        /**
-         * Get the instance of the class
-         * and replace the lazy proxy with the instance
-         * for performance optimization.
-         */
-        const getAndRegisterInstance = (): void => {
-            if (instance == null) {
-                if (init) {
-                    instance = init(constructor);
-                } else {
-                    instance = new constructor();
-                }
-            }
-            diContainer.register(_identifier, instance);
-        };
-
-        // Create a proxy to instantiate the class when needed (Lazy Initialization)
-        const lazyProxy: unknown = new Proxy(
-            {},
-            {
-                get(_target, prop, _receiver) {
-                    getAndRegisterInstance();
-
-                    // Return the requested property of the instance
-                    return instance[prop as keyof InstanceType<TargetType>];
-                },
-                set(_target, prop, value, _receiver) {
-                    getAndRegisterInstance();
-
-                    // Set the requested property of the instance
-                    return (instance[prop as keyof InstanceType<TargetType>] =
-                        value);
-                },
-            },
-        );
-
-        diContainer.register(_identifier, lazyProxy);
-    };
 }

src/functions/inject.ts

@@ -0,0 +1,220 @@
+import { TSinjex } from '../classes/TSinjex.js';
+import {
+    DependencyResolutionError,
+    InitializationError,
+    InjectorError,
+    NoInstantiationMethodError,
+} from '../interfaces/Exceptions.js';
+import { Identifier } from '../types/Identifier.js';
+import { InitDelegate } from '../types/InitDelegate.js';
+
+/**
+ * Resolves a dependency by its identifier without initialization or instantiation.
+ * @template T The expected type of the dependency.
+ * @param identifier The identifier used to resolve the dependency from the container.
+ * @returns The resolved dependency.
+ * @throws A {@link DependencyResolutionError} if the dependency is not found.
+ * @example
+ * ```ts
+ * const logger = inject<Logger>('Logger');
+ * ```
+ */
+export function inject<T>(identifier: Identifier): T;
+
+/**
+ * Resolves and instantiates a dependency using its constructor.
+ * @template T The expected class type of the dependency.
+ * @param identifier The identifier used to resolve the dependency from the container.
+ * @param shouldInit Set to `true` to instantiate the dependency after resolution.
+ * @returns The resolved and instantiated dependency.
+ * @throws A {@link DependencyResolutionError} if the dependency is not found.
+ * @throws A {@link NoInstantiationMethodError} if the dependency has no constructor.
+ * @throws An {@link InitializationError} if instantiation fails.
+ * @example
+ * ```ts
+ * const instance = inject<Service>('Service', true);
+ * ```
+ */
+export function inject<T>(identifier: Identifier, shouldInit: true): T;
+
+/**
+ * Resolves and instantiates a dependency using its constructor, optionally failing silently.
+ * @template T The expected class type of the dependency.
+ * @param identifier The identifier used to resolve the dependency from the container.
+ * @param shouldInit Set to `true` to instantiate the dependency.
+ * @param isNecessary If `false`, resolution or instantiation errors return `undefined` instead of throwing.
+ * @returns The resolved and instantiated dependency, or `undefined` if resolution or instantiation fails.
+ * @example
+ * ```ts
+ * const instance = inject<Service>('OptionalService', true, false);
+ * if (instance) instance.doSomething();
+ * ```
+ */
+export function inject<T>(
+    identifier: Identifier,
+    shouldInit: true,
+    isNecessary: false,
+): T | undefined;
+
+/**
+ * Resolves a dependency without instantiating it, optionally failing silently.
+ * @template T The expected type of the dependency.
+ * @param identifier The identifier used to resolve the dependency from the container.
+ * @param shouldInit Set to `false` to skip instantiation.
+ * @param isNecessary If `false`, resolution errors return `undefined` instead of throwing.
+ * @returns The resolved dependency, or `undefined` if not found.
+ * @example
+ * ```ts
+ * const config = inject<Config>('Config', false, false) ?? getDefaultConfig();
+ * ```
+ */
+export function inject<T>(
+    identifier: Identifier,
+    shouldInit: false,
+    isNecessary: false,
+): T | undefined;
+
+/**
+ * Resolves a dependency and applies a custom initializer function to transform the result.
+ * @template T The original dependency type.
+ * @template U The final return type after initialization.
+ * @param identifier The identifier used to resolve the dependency.
+ * @param init A function to transform or initialize the dependency.
+ * @returns The transformed dependency.
+ * @throws A {@link DependencyResolutionError} if the dependency is not found.
+ * @throws An {@link InitializationError} if the initializer throws.
+ * @example
+ * ```ts
+ * const client = inject<Api>('Api', (api) => api.getClient());
+ * ```
+ */
+export function inject<T, U>(
+    identifier: Identifier,
+    init: InitDelegate<T, U>,
+): U;
+
+/**
+ * Resolves a dependency and applies a custom initializer function, optionally failing silently.
+ * @template T The original dependency type.
+ * @template U The final return type after initialization.
+ * @param identifier The identifier used to resolve the dependency.
+ * @param init A function to transform or initialize the dependency.
+ * @param isNecessary If `false`, resolution or initializer errors return `undefined` instead of throwing.
+ * @returns The transformed dependency, or `undefined` if resolution or initialization fails.
+ * @example
+ * ```ts
+ * const db = inject<Database, Pool>('Database', (d) => d.getPool(), false);
+ * if (db) db.query('SELECT * FROM users');
+ * ```
+ */
+export function inject<T, U>(
+    identifier: Identifier,
+    init: InitDelegate<T, U>,
+    isNecessary: false,
+): U | undefined;
+
+/**
+ * A function to inject a dependency from a DI (Dependency Injection) container into a variable.
+ * This is the actual implementation that handles all overload variants.
+ * @template T The original dependency type.
+ * @template U The final return type after optional initialization or transformation.
+ * @param identifier The identifier used to resolve the dependency.
+ * @see {@link Identifier} for more information on identifiers.
+ * @param init Optional: either `true` to instantiate via constructor, `false` to skip, or a function to transform the dependency.
+ * @see {@link InitDelegate} for more information on initializer functions.
+ * @param isNecessary If `true`, throws on failure; if `false`, returns `undefined` on resolution or initialization errors.
+ * @returns The resolved dependency or result of initialization, or `undefined` if not necessary and resolution fails.
+ * @throws A {@link DependencyResolutionError} if the dependency is not found (and necessary).
+ * @throws A {@link NoInstantiationMethodError} if instantiation is requested but no constructor exists.
+ * @throws An {@link InitializationError} if the initializer throws an error.
+ * @throws A {@link InjectorError} for unknown errors during resolution or transformation.
+ * @example
+ * ```ts
+ * const service = inject<Service>('Service');
+ * ```
+ * @example
+ * ```ts
+ * const instance = inject<Service>('Service', true);
+ * ```
+ * @example
+ * ```ts
+ * const logger = inject<ILogger>('ILogger_', (x) => x.getLogger('Module'), false);
+ * ```
+ */
+export function inject<T, U>(
+    identifier: Identifier,
+    init?: InitDelegate<T, U> | true | false,
+    isNecessary = true,
+): T | U | undefined {
+    let instance: T | U | undefined;
+
+    const dependency: T | undefined = tryAndCatch(
+        () => TSinjex.getInstance().resolve<T>(identifier, isNecessary),
+        isNecessary,
+        identifier,
+        DependencyResolutionError,
+    );
+
+    if (dependency != null) {
+        const initFunction: (() => U) | undefined =
+            typeof init === 'function' && dependency != null
+                ? (): U => init(dependency)
+                : init === true && hasConstructor(dependency)
+                  ? (): U => new dependency() as U
+                  : undefined;
+
+        if (init == null || init === false) instance = dependency;
+        else if (initFunction != null)
+            instance = tryAndCatch(
+                initFunction,
+                isNecessary,
+                identifier,
+                InitializationError,
+            );
+        else if (isNecessary) throw new NoInstantiationMethodError(identifier);
+    } else if (isNecessary) throw new DependencyResolutionError(identifier);
+
+    return instance as T | U;
+}
+
+/**
+ * Tries to execute a function and catches any errors that occur.
+ * If the function is necessary and an error occurs, it throws the error
+ * with the specified error class and identifier.
+ * @param fn The function to execute.
+ * @param necessary If true, throws an error if an error occurs.
+ * @param identifier The identifier of the dependency.
+ * @param errorClass The error class to throw if an error occurs.
+ * @returns The result of the function or undefined if an error occurs and the function is not necessary.
+ */
+function tryAndCatch<ReturnType, ErrorType>(
+    fn: () => ReturnType,
+    necessary: boolean,
+    identifier?: Identifier,
+    errorClass?: ErrorType,
+): ReturnType | undefined {
+    try {
+        return fn();
+    } catch (error) {
+        if (necessary)
+            throw new (errorClass != null ? errorClass : error)(
+                identifier ?? 'not specified',
+                error,
+            );
+        else return undefined;
+    }
+}
+
+/**
+ * Checks if an object has a constructor.
+ * @param obj The object to check.
+ * @returns True if the object has a constructor, false otherwise.
+ */
+function hasConstructor<T>(obj: T): obj is T & { new (): unknown } {
+    const _obj = obj as unknown as { prototype?: { constructor?: unknown } };
+
+    return (
+        _obj?.prototype != null &&
+        typeof _obj.prototype.constructor === 'function'
+    );
+}

src/functions/register.ts

@@ -1,5 +1,5 @@
-import { TSinjex } from '../classes/TSinjex';
+import { TSinjex } from '../classes/TSinjex.js';
-import { Identifier } from '../types/Identifier';
+import { Identifier } from '../types/Identifier.js';
 
 /**
  * Register a dependency.

src/functions/resolve.ts

@@ -1,6 +1,6 @@
-import { TSinjex } from '../classes/TSinjex';
+import { TSinjex } from '../classes/TSinjex.js';
-import { DependencyResolutionError } from '../interfaces/Exceptions';
+import { DependencyResolutionError } from '../interfaces/Exceptions.js';
-import { Identifier } from '../types/Identifier';
+import { Identifier } from '../types/Identifier.js';
 
 /**
  * Resolve a dependency.
@@ -15,12 +15,12 @@ export function resolve<T>(identifier: Identifier): T;
  * Resolve a dependency
  * @param identifier The identifier used to register the class in the DI container.
  * @see {@link Identifier} for more information on identifiers.
- * @param necessary The dependency is **not** necessary.
+ * @param isNecessary The dependency is **not** necessary.
  * @returns The resolved dependency or undefined if the dependency is not found.
  */
 export function resolve<T>(
     identifier: Identifier,
-    necessary: false,
+    isNecessary: false,
 ): T | undefined;
 
 /**

src/index.ts

@@ -1,18 +1,22 @@
 /* istanbul ignore file */
 
 // Main
-export * from './classes/TSinjex';
+export * from './classes/TSinjex.js';
 
 // Decorators
-export * from './decorators/Inject';
+export * from './decorators/Inject.js';
-export * from './decorators/Register';
+export * from './decorators/Register.js';
-export * from './decorators/RegisterInstance';
+export * from './decorators/RegisterInstance.js';
+
+// Helper
+export * from './helper/ImplementsStatic.js';
 
 // Functions
-export * from './functions/resolve';
+export * from './functions/resolve.js';
-export * from './functions/register';
+export * from './functions/register.js';
+export * from './functions/inject.js';
 
 // Interfaces & Types
-export type * from './interfaces/ITSinjex';
+export type * from './interfaces/ITSinjex.js';
-export type * from './types/InitDelegate';
+export type * from './types/InitDelegate.js';
-export type * from './types/GenericContructor';
+export type * from './types/GenericContructor.js';

src/interfaces/Exceptions.ts

@@ -1,5 +1,5 @@
-import { Identifier } from 'src/types/Identifier';
+import { Identifier } from 'src/types/Identifier.js';
-import { ITSinjex } from './ITSinjex';
+import { ITSinjex } from './ITSinjex.js';
 
 /**
  * General error class for {@link ITSinjex} interface.
@@ -15,19 +15,6 @@ export class TSinjexError extends Error {
     }
 }
 
-/**
- * Error class for missing identifiers in {@link ITSinjex} methods.
- */
-export class IdentifierRequiredError extends TSinjexError {
-    /**
-     * Creates a new instance of {@link IdentifierRequiredError}
-     */
-    constructor() {
-        super('Identifier is required.');
-        this.name = 'TSinjexIdentifierRequiredError';
-    }
-}
-
 /**
  * Error class for dependency resolution errors in {@link ITSinjex}.
  * @see {@link ITSinjex.resolve}

src/interfaces/ITSinjex.ts

@@ -1,5 +1,5 @@
-import { DependencyResolutionError } from './Exceptions';
+import { DependencyResolutionError } from './Exceptions.js';
-import { Identifier } from '../types/Identifier';
+import { Identifier } from '../types/Identifier.js';
 
 /**
  * Static TSInjex Interface

tsconfig.json

@@ -7,17 +7,19 @@
         "declaration": true,
         "declarationMap": true,
         "outDir": "./dist",
-        "module": "ESNext",
+        "module": "NodeNext",
-        "target": "ES6",
+        "target": "ES2020",
         "allowJs": true,
         "noUnusedLocals": false,
         "noUnusedParameters": false,
         "noImplicitAny": true,
-        "moduleResolution": "node",
+        "moduleResolution": "NodeNext",
         "allowSyntheticDefaultImports": true,
         "importHelpers": true,
         "isolatedModules": true,
         "resolveJsonModule": true,
+        "experimentalDecorators": true,
+        "emitDecoratorMetadata": true,
         "strictNullChecks": true,
         "strictPropertyInitialization": true,
         "lib": [