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@bleed-believer/path-alias

A comprehensive library designed to streamline the execution of TypeScript code with SWC. It offers a variety of features aimed at simplifying TypeScript project setup and improving efficiency. Key functionalities include:

  • Direct TypeScript Execution: Run TypeScript files directly through an integrated CLI or by using the --import flag, powered by SWC.
  • Minimal Configuration: Requires only the project's tsconfig.json to operate, making setup quick and straightforward.
  • Path Alias Resolution: Automatically resolves path aliases defined in tsconfig.json, allowing you to use more readable imports without complex configurations.
  • Internal Transpilation with Resolved Aliases: Transpiles TypeScript files internally, producing JavaScript code with resolved path aliases, ready for direct execution with Node.js.
  • Support for Pre-Transpiled Projects: Capable of executing pre-transpiled projects that may not have resolved path aliases, ensuring compatibility across different project setups.
  • Source Map Generation: Generates source maps for seamless debugging, allowing you to debug directly in TypeScript with accurate mappings to the original code.

By using @bleed-believer/path-alias, you can replace cumbersome relative imports, such as:

import { UserController } from '../../../../controllers/user/user-controller.js';
import { CSVGenerator } from '../../../tool/csv-generator.js';
import { AuthService } from '../../../services/auth/auth-service.js';
import { Client } from '../../../../entities/client.js';

...with cleaner and more intuitive path aliases, like:

import { UserController } from '@controllers/user/user-controller.js';
import { CSVGenerator } from '@tool/csv-generator.js';
import { AuthService } from '@services/auth/auth-service.js';
import { Client } from '@entities/client.js';

Disclaimer

This library has been completely rewritten from the ground up, removing all dependencies on ts-node in favor of SWC for faster and more efficient TypeScript transpilation. Please note that this represents a breaking change compared to version 1.1.3, as both the execution process and core functionality have been significantly altered. Upgrading to this version may require updates to your current project setup to align with these new capabilities and configurations.

Usage Guide

  1. Install the library:

    npm i --save @bleed-believer/path-alias

  2. Configure your tsconfig.json:

    @bleed-believer/path-alias automatically translates your TypeScript configuration from tsconfig.json to a format that SWC can interpret. Let’s break down how the configuration is adapted:

    • Compiler Options:

      • The target and module settings (e.g., "ES2022" and "Node16") define how the code will be compiled, specifying the ECMAScript version and module system.
      • SWC is configured to recognize TypeScript syntax, and settings like emitDecoratorMetadata and experimentalDecorators enable support for decorators.
      • sourceMap and inlineSources determine whether source maps are generated inline for debugging.

    • Path Aliases:

      • The baseUrl and paths options in your tsconfig.json allow you to define aliases for directories within your project. For example, @greetings/* maps to ./greetings/*.
      • The library automatically resolves these path aliases during transpilation, so your JavaScript output reflects these simpler import paths.

    • Module Settings:

      • @bleed-believer/path-alias ensures compatibility with "module" values like Node16 and ES2022. When using modules not supported by SWC, it throws an error for unsupported configurations, ensuring clarity and consistency in your setup.

    Here’s an example of a compatible tsconfig.json:

    {
  "compilerOptions": {
    "target": "ES2022",
    "module": "Node16",
    "moduleResolution": "Node16",

    "strict": true,
    "verbatimModuleSyntax": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,

    "outDir": "./dist",
    "rootDir": "./src",
    "baseUrl": "./src",

    "paths": {
      "@greetings/*": [ "./greetings/*" ],
      "@tool/*": [ "./tool/*" ]
    }
  }
}

  3. Run your code: You can now execute your TypeScript code with the following commands:

    # To run using the CLI
npx bb-path-alias start ./src/index.ts

# To run using the --import flag
node --import @bleed-believer/path-alias ./src/index.ts

Run Already Transpiled Code

If you have pre-transpiled code but your path aliases haven't been resolved, you can use this library to execute that code directly:

# To run using the CLI
npx bb-path-alias start ./dist/index.js

# To run using the --import flag
node --import @bleed-believer/path-alias ./dist/index.js

Transpile the Project

To transpile your project using the integrated CLI, follow these commands:

# Transpile using the default configuration at ./tsconfig.json
npx bb-path-alias build

# Transpile using a custom configuration file
npx bb-path-alias build ./tsconfig.build.json

This functionality makes it easy to switch between direct execution and manual transpilation, allowing you to resolve path aliases seamlessly in both workflows.

Utils

The following utility functions enhance the functionality of @bleed-believer/path-alias by providing additional support for handling TypeScript source files and resolving paths dynamically based on the code's context.

isSourceCode(url: string)

This function determines whether the provided URL corresponds to a TypeScript source file.

  • Parameters:

    • url (string): The URL or file path to check.

  • Returns: true if the URL corresponds to a TypeScript file, false otherwise.

  • Usage: This function is especially useful for conditional logic based on the file type (TypeScript vs. JavaScript). For example, if certain operations should only be performed on TypeScript files, this function helps enforce that condition.

  • Example:

    // Checking if a file is TypeScript
const isTs = isSourceCode('/path/to/file.ts');
console.log(isTs); // Output: true

// Checking if a file is JavaScript
const isTs = isSourceCode('/path/to/file.js');
console.log(isTs); // Output: false

    This example demonstrates how to use isSourceCode to check the file type based on its extension.

pathResolve(input: string, options?: { url?: string; multi?: boolean })

This function resolves the absolute path(s) of the specified input, adapting based on whether the code is running in TypeScript or JavaScript mode, and the provided options.

  • Parameters:

    • input (string): The relative path or alias to resolve.
    • options (object, optional):
      • url (string, optional): The URL or file path of the calling module. This is used to determine if the calling code is TypeScript or JavaScript, based on the file extension. If not provided, the function assumes the calling code is TypeScript.
      • multi (boolean, optional): If set to true, returns an array of resolved paths. Defaults to false.

  • Returns:

    • When multi is false or not provided, it returns a single string path.
    • When multi is true, it returns an array of string paths.

  • Functionality:

    • The function uses the tsconfig.json configuration to resolve paths and aliases.
    • If the calling code is determined to be JavaScript (e.g., if options.url has a .js extension), the resolved paths will point to the compiled JavaScript files in the outDir directory.
    • If the calling code is TypeScript (e.g., if options.url has a .ts extension or if url is not provided), the resolved paths will point to the source TypeScript files in the rootDir directory.

  • Example:

    // In a TypeScript file, resolving a single path
const singlePath = pathResolve(
  '@tool/example.ts',
  { url: import.meta.url }
);

console.log(singlePath); 
// Output: /absolute/path/to/src/tool/example.ts

// In a JavaScript file, resolving a single path
const singlePath = pathResolve(
  '@tool/example.ts',
  { url: import.meta.url }
);

console.log(singlePath); 
// Output: /absolute/path/to/dist/tool/example.js

// Resolving multiple paths in TypeScript
const multiplePaths = pathResolve('@greetings/*.ts', {
  multi: true,
  url: import.meta.url
});

console.log(multiplePaths);
// Output: ['/absolute/path/to/src/greetings/hello.ts', '/absolute/path/to/src/greetings/welcome.ts', ...]

    This example shows how to use pathResolve to obtain the correct file paths based on the execution context and provided options.

Unit Testing

The library is compatible with AVA (and likely with most testing libraries that support the --import flag). To use AVA with @bleed-believer/path-alias, simply create a ava.config.mjs file at the root of your project with the following configuration:

export default {
  files: [
    './src/**/*.test.ts',
    './src/**/*.test.mts',
  ],
  extensions: {
    ts: 'module',
    mts: 'module',
  },
  nodeArguments: [
    '--import=@bleed-believer/path-alias'
  ]
}

Explanation:

  • files: Specifies the patterns for test files. Here, it's set to include any .test.ts or .test.mts files within the src directory and its subdirectories.
  • extensions: Configures AVA to treat .ts and .mts files as ES modules.
  • nodeArguments: Adds the --import flag for @bleed-believer/path-alias, enabling path alias resolution for your tests.

This setup ensures that AVA can correctly resolve and execute tests written in TypeScript, leveraging the path aliases defined in your tsconfig.json.