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Linting

In this tutorial, we'll learn about linting and how to use linting tools, such as ESLint, to enforce code quality and consistency in your TypeScript projects.

What is Linting?​

Linting is the process of analyzing your code for potential errors, stylistic issues, and inconsistencies. A linter is a tool that helps you maintain code quality and ensure that your code follows best practices and coding standards.

Setting up ESLint​

ESLint is a popular linting tool for JavaScript and TypeScript projects. To set up ESLint for your TypeScript project, follow these steps:

  1. Install ESLint and its TypeScript parser:
npm install eslint @typescript-eslint/parser --save-dev
  1. Install the recommended ESLint plugin for TypeScript:
npm install @typescript-eslint/eslint-plugin --save-dev
  1. Create an ESLint configuration file (.eslintrc.js) in your project root:
JavaScript
module.exports = {
  parser: '@typescript-eslint/parser',
  plugins: ['@typescript-eslint'],
  extends: ['eslint:recommended', 'plugin:@typescript-eslint/recommended'],
  rules: {
    // Add custom rules here
  },
};

This configuration sets up ESLint to use the TypeScript parser and plugin, and extends the recommended set of rules for TypeScript.

Configuring ESLint Rules​

ESLint comes with a set of built-in rules that you can enable, disable, or customize in your configuration file. You can also use third-party plugins to add more rules.

For example, to enforce the use of single quotes and disallow the use of any, add the following rules to your .eslintrc.js file:

JavaScript
rules: {
  'quotes': ['error', 'single'],
  '@typescript-eslint/no-explicit-any': 'error',
},

For a full list of available rules, refer to the ESLint documentation.

Running ESLint​

To run ESLint on your TypeScript files, add the following script to your package.json:

JSON
{
  "scripts": {
    "lint": "eslint --ext .ts,.tsx src/"
  }
}

This script will run ESLint on all .ts and .tsx files in the src directory. To run the linter, execute the following command:

npm run lint

Conclusion​

In this tutorial, we've learned about linting and how to set up and configure ESLint for TypeScript projects. Linting is an essential practice for maintaining code quality and consistency in your projects. By using linting tools like ESLint, you can enforce best practices and coding standards, ensuring that your code is clean and easy to maintain.