TypeScript Academy · Lesson

ESLint + @typescript-eslint

Set up ESLint with @typescript-eslint plugin to catch type-aware issues and enforce consistent style.

Lesson 1 of 38 steps

ESLint + @typescript-eslint is a free TypeScript Academy lesson on CoddyKit. This is lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the TypeScript Academy learning path, and your progress syncs across the web and the CoddyKit app. The TypeScript Academy course includes 3 lessons in total.

Intro

Goal: Use ESLint with @typescript-eslint to catch bugs and enforce style in TypeScript projects.

Install

Install core ESLint plus @typescript-eslint/parser and @typescript-eslint/eslint-plugin.

npm install --save-dev eslint @typescript-eslint/parser @typescript-eslint/eslint-plugin

Config

Configure ESLint to use the TS parser and recommended rules. Add project-specific rules as needed.

// .eslintrc.js
module.exports = {
  parser: "@typescript-eslint/parser",
  plugins: ["@typescript-eslint"],
  extends: [
    "eslint:recommended",
    "plugin:@typescript-eslint/recommended"
  ],
  rules: {
    "@typescript-eslint/no-unused-vars": "warn"
  }
};

Example lint

ESLint highlights missing arguments, unused vars, and style issues when using the TS-aware parser.

// demo.ts
function greet(name: string) {
  console.log("Hello", name)
}

greet("Ada")

greet() // ESLint error: missing arg

Type-aware rules

Link to tsconfig.json in parserOptions for rules that need type info, e.g., detecting unhandled promises.

// tsconfig.json must be linked for type-aware rules
{
  "parserOptions": {
    "project": "./tsconfig.json"
  }
}

// Example: no-floating-promises
async function f() {
  fetch("/api") // ESLint error: unhandled promise
}

Run lint

Run ESLint on your codebase. Add --fix to auto-apply safe fixes.

npx eslint "src/**/*.{ts,tsx}" --fix

Question

Quick check: Why use @typescript-eslint in addition to ESLint core?

Answer it in the interactive lesson

Recap

Recap: Install ESLint + @typescript-eslint, configure parser, extend recommended, run linter with type-aware rules for clean code.

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Frequently Asked Questions

Is the “ESLint + @typescript-eslint” lesson free?

Yes — the full text of “ESLint + @typescript-eslint” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the TypeScript Academy course, upgrade to CoddyKit PRO. The TypeScript Academy course includes 3 lessons in total.

What will I learn in “ESLint + @typescript-eslint”?

Set up ESLint with @typescript-eslint plugin to catch type-aware issues and enforce consistent style. You practise TypeScript Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start TypeScript Academy?

No prior experience is required. TypeScript Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 3.

How long does the “ESLint + @typescript-eslint” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this TypeScript Academy lesson?

Yes. Every TypeScript Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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