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TS Definitely Typed

Definitely Typed is a repository of high-quality TypeScript type definitions for popular JavaScript libraries. It enables seamless integration of JavaScript libraries with strong typing, enhancing the TypeScript development experience.

Key Topics

What is Definitely Typed?

Definitely Typed is a community-driven repository that hosts type definitions for JavaScript libraries. These type definitions are written and maintained by the TypeScript community, providing type support for libraries that don’t ship with built-in TypeScript definitions.

https://github.com/DefinitelyTyped/DefinitelyTyped

Explanation: Developers can find and contribute type definitions for various JavaScript libraries in the Definitely Typed repository.

Installing Types

To use type definitions from Definitely Typed, you can install them using the @types namespace from npm.

npm install --save-dev @types/lodash

Output

+ @types/lodash@latest

added 1 package in 1.23s

Explanation: This command installs type definitions for the lodash library, allowing TypeScript to recognize and validate its API.

Using Installed Types

Once installed, you can import and use the library with full type support.

import _ from "lodash";

const numbers = [1, 2, 3, 4];
const doubled = _.map(numbers, (n) => n * 2);
console.log(doubled); // [2, 4, 6, 8]

Output

[2, 4, 6, 8]

Explanation: The installed types enable IntelliSense, auto-completion, and compile-time type checking for the lodash library, ensuring error-free usage.

Key Takeaways

  • What is Definitely Typed: A community-driven repository for TypeScript type definitions.
  • Installing Types: Use npm to install type definitions under the @types namespace.
  • Using Types: Installed types provide IntelliSense, auto-completion, and compile-time checking.
  • Best Practice: Always install type definitions for libraries that lack built-in TypeScript support.
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