TypeScript Course
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Beginner

tsconfig.json

Definition

The configuration file that indicates that a directory is the root of a TypeScript project. It specifies the root files and the compiler options required to compile the project.

Explain Like I'm New

The `tsconfig.json` is the rulebook for the TypeScript Sheriff. It tells the compiler exactly how strict it should be, what files it should ignore (like `node_modules`), and what 'flavor' of JavaScript it should output (like old ES5 for Internet Explorer, or modern ES2022).

Real World Example

Running `tsc --init` in a terminal creates a blank `tsconfig.json`. Changing `"target": "ES6"` tells the compiler to leave Arrow Functions alone, rather than compiling them down to `function() {}` for old browsers.

Common Use Cases

  • •Project setup
  • •Adjusting compiler strictness
  • •Excluding test files from the build

Interactive Example

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Interview Questions

basic

  • What command generates a default `tsconfig.json`?

intermediate

  • What is the difference between `include` and `exclude`?

advanced

  • What does the `extends` property do in a tsconfig?

Flash Cards

Question

What command generates it?

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Answer

`npx tsc --init` (if using npx) or simply `tsc --init` if installed globally.

Question

What does the extends property do?

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Answer

It allows a `tsconfig.json` to inherit from another configuration file. Large monorepos usually have a `tsconfig.base.json` at the root, and each sub-project has a tiny tsconfig that just does `"extends": "../../tsconfig.base.json"`.