TypeScript Checking Extra File that Not Specified in “files”: The Ultimate Guide

TypeScript is an amazing tool for developers, offering a plethora of features to enhance code maintainability, readability, and scalability. However, like any powerful tool, it requires proper configuration to work seamlessly. One common issue that many developers face is TypeScript checking extra files that are not specified in the “files” configuration. In this article, we’ll dive deep into the problem, explore the reasons behind it, and provide you with a step-by-step guide to resolve the issue.

The Problem: TypeScript Checking Extra Files

Imagine you’re working on a TypeScript project, and everything seems to be working fine. You’ve configured your `tsconfig.json` file, and TypeScript is compiling your code without any issues. But, suddenly, you notice that TypeScript is checking files that you didn’t specify in the “files” configuration. This can be frustrating, especially if you’re working on a large project with many files and folders.

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "files": [
    "src/index.ts"
  ]
}

In the above example, you’d expect TypeScript to only compile the `src/index.ts` file. However, TypeScript might start checking other files in the `src` directory or even other directories, leading to unnecessary compilation and potential errors.

Why is TypeScript Checking Extra Files?

There are several reasons why TypeScript might be checking extra files that are not specified in the “files” configuration. Here are some common causes:

• Imports and References: If you’re importing or referencing other files in your code, TypeScript will automatically include them in the compilation process.
• Glob Patterns: Using glob patterns in the “files” or “include” configurations can lead to unexpected file inclusions.
• Duplicate File Names: If you have files with the same name in different directories, TypeScript might get confused and include the wrong files.
• Inconsistent File Extensions: Mixing file extensions like `.ts`, `.tsx`, and `.js` can cause TypeScript to include unnecessary files.

Solving the Issue: Step-by-Step Guide

To resolve the issue of TypeScript checking extra files, follow these steps:

1. Check Your tsconfig.json File: Review your `tsconfig.json` file and ensure that you haven’t accidentally included unnecessary files or directories.

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "files": [
    "src/index.ts"
  ]
}

2. Verify Your Imports and References: Check your code for any unnecessary imports or references. Make sure you’re not importing files that you don’t need.

// src/index.ts
import { MyClass } from './myClass';
// ...

3. Use Specific File Extensions: Ensure that you’re using consistent file extensions throughout your project. If you’re using `.ts` files, avoid including `.js` files in your configuration.

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "files": [
    "src/index.ts"
  ]
}

4. Avoid Glob Patterns: Refrain from using glob patterns in your “files” or “include” configurations. Instead, specify individual files or directories explicitly.

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "files": [
    "src/index.ts",
    "src/myClass.ts"
  ]
}

5. Use the “include” Option: If you have a large project with many files, use the “include” option to specify which directories or files should be included in the compilation process.

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "include": [
    "src/**/*.ts"
  ]
}

6. Check for Duplicate File Names: Ensure that you don’t have duplicate file names in different directories. If you do, consider renaming them to avoid confusion.

// src/myFile.ts
// src/subdir/myFile.ts (rename to myFile2.ts)

7. Verify Your Project Structure: Finally, review your project structure and ensure that it’s organized and consistent. This will help you avoid unnecessary file inclusions and make it easier to manage your project.

Additional Tips and Tricks

To further optimize your TypeScript configuration and avoid unnecessary file checking, consider the following tips and tricks:

• Use the “exclude” Option: If you have certain files or directories that you don’t want to include in the compilation process, use the “exclude” option.

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "include": [
    "src/**/*.ts"
  ],
  "exclude": [
    "src/excludeMe.ts"
  ]
}

• Specify Individual Files: Instead of using glob patterns or directories, specify individual files in your “files” or “include” configurations.

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "files": [
    "src/index.ts",
    "src/myClass.ts",
    "src/anotherFile.ts"
  ]
}

• Use a Separate tsconfig.json File for each Project: If you’re working on multiple projects, consider using a separate `tsconfig.json` file for each project. This will help you avoid configuration conflicts and ensure that each project is configured correctly.

// project1/tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "sourceMap": true,
    "outDir": "build"
  },
  "files": [
    "src/index.ts"
  ]
}

// project2/tsconfig.json
{
  "compilerOptions": {
    "target": "es6",
    "module": "esnext",
    "sourceMap": true,
    "outDir": "build"
  },
  "files": [
    "src/main.ts"
  ]
}

Conclusion

TypeScript is a powerful tool that can greatly enhance your development experience. However, improper configuration can lead to issues like TypeScript checking extra files that are not specified in the “files” configuration. By following the steps outlined in this article, you can resolve this issue and ensure that your TypeScript configuration is optimized for your project’s needs.