DefinitelyTyped

The repository for high quality TypeScript type definitions.

Also see the definitelytyped.org website, although information in this README is more up-to-date.

What are declaration files?

See the TypeScript handbook.

How do I get them?

npm

This is the preferred method. This is only available for TypeScript 2.0+ users. For example:

npm install --save-dev @types/node

The types should then be automatically included by the compiler. See more in the handbook.

For an NPM package "foo", typings for it will be at "@types/foo". If you can't find your package, look for it on TypeSearch.

If you still can't find it, check if it bundles its own typings. This is usually provided in a "types" or "typings" field in the package.json, or just look for any ".d.ts" files in the package and manually include them with a /// <reference path="" />.

Other methods

These can be used by TypeScript 1.0.

• Typings
• NuGet
• Manually download from the master branch of this repository

You may need to add manual references.

How can I contribute?

DefinitelyTyped only works because of contributions by users like you!

Test

Before you share your improvement with the world, use it yourself.

Test editing an existing package

To add new features you can use module augmentation. You can also directly edit the types in node_modules/@types/foo/index.d.ts, or copy them from there and follow the steps below.

Test a new package

Add to your tsconfig.json:

"baseUrl": "types",
"typeRoots": ["types"],

(You can also use src/types.) Create types/foo/index.d.ts containing declarations for the module "foo". You should now be able import from "foo" in your code and it will route to the new type definition. Then build and run the code to make sure your type definition actually corresponds to what happens at runtime. Once you've tested your definitions with real code, make a PR contributing the definition by copying types/foo to DefinitelyTyped/foo and adding a tsconfig.json and foo-tests.ts.

Make a pull request

Once you've tested your package, you can share it on DefinitelyTyped.

First, fork this repository, install node, and run npm install.

Edit an existing package

• cd my-package-to-edit
• Make changes. Remember to edit tests.
• You may also want to add yourself to "Definitions by" section of the package header.
• npm install -g typescript@2.0 and run tsc.

When you make a PR to edit an existing package, dt-bot should @-mention previous authors. If it doesn't, you can do so yourself in the comment associated with the PR.

Create a new package

If you are the library author, or can make a pull request to the library, bundle types instead of publishing to DefinitelyTyped.

If you are adding typings for an NPM package, create a directory with the same name. If the package you are adding typings for is not on NPM, make sure the name you choose for it does not conflict with the name of a package on NPM. (You can use npm info foo to check for the existence of the foo package.)

Your package should have this structure:

File	Purpose
index.d.ts	This contains the typings for the package.
foo-tests.ts	This contains sample code which tests the typings. This code does not run, but it is type-checked.
tsconfig.json	This allows you to run tsc within the package.
tslint.json	Enables linting.

Generate these by running npm run new-package -- new-package-name.

You may edit the tsconfig.json to add new files or to add the "jsx" compiler option.

DefinitelyTyped members routinely monitor for new PRs, though keep in mind that the number of other PRs may slow things down.

For a good example package, see base64-js.

Common mistakes

• First, follow advice from the handbook.
• Formatting: Either use all tabs, or always use 4 spaces. Also, always use semicolons, and use egyptian braces.
• interface X {}: An empty interface is essentially the {} type: it places no constraints on an object.
• interface IFoo {}: Don't add I to the front of an interface name.
• interface Foo { new(): Foo; }: This defines a type of objects that are new-able. You probably want declare class Foo { constructor(); }.
• const Class: { new(): IClass; }: Prefer to use a class declaration class Class { constructor(); } instead of a new-able constant.
• namespace foo {}: Do not add a namespace just so that the import * as foo syntax will work. If it is commonJs module with a single export, you should use the import foo = require("foo") syntax. See more explanation here.
• getMeAT<T>(): T: If a type parameter does not appear in the types of any parameters, you don't really have a generic function, you just have a disguised type assertion. Prefer to use a real type assertion, e.g. getMeAT() as number. Example where a type parameter is acceptable: function id<T>(value: T): T;. Example where it is not acceptable: function parseJson<T>(json: string): T;. Exception: new Map<string, number>() is OK.

Removing a package

When a package bundles its own types, types should be removed from DefinitelyTyped to avoid confusion.

You can remove it by running npm run not-needed -- typingsPackageName asOfVersion sourceRepoURL [libraryName].

• typingsPackageName: This is the name of the directory to delete.
• asOfVersion: A stub will be published to @types/foo with this version. Should be higher than any currently published version.
• sourceRepoURL: This should point to the repository that contains the typings.
• libraryName: Descriptive name of the library, e.g. "Angular 2" instead of "angular2". (If ommitted, will be identical to "typingsPackageName".)

Any other packages in DefinitelyTyped that referenced the deleted package should be updated to reference the bundled types. To do this, add a package.json with "dependencies": { "foo": "x.y.z" }.

If a package was never on DefinitelyTyped, it does not need to be added to notNeededPackages.json.

Lint

To lint a package, just add a tslint.json to that package containing { "extends": "../tslint.json" }. All new packages must be linted. If a tslint.json turns rules off, this is because that hasn't been fixed yet. For example:

{
    "extends": "../tslint.json",
    "rules": {
        // This package uses the Function type, and it will take effort to fix.
        "forbidden-types": false
    }
}

(To indicate that a lint rule truly does not apply, use // tslint:disable:rule-name or better, //tslint:disable-next-line:rule-name.)

Only .d.ts files are linted. Test the linter by running npm run lint -- package-name. Do not use a globally installed tslint.

FAQ

What exactly is the relationship between this repository and the @types packages on NPM?

The master branch is automatically published to the @types scope on NPM thanks to types-publisher. This usually happens within an hour of changes being merged.

I'm writing a definition that depends on another definition. Should I use <reference types="" /> or an import?

If the module you're referencing is an external module (uses export), use an import. If the module you're referencing is an ambient module (uses declare module, or just declares globals), use <reference types="" />.

What do I do about older versions of typings?

Currently we don't support this, though it is planned. If you're adding a new major version of a library, you can copy index.d.ts to foo-v2.3.d.ts and edit index.d.ts to be the new version.

I notice some packages having a package.json here.

Usually you won't need this. When publishing a package we will normally automatically create a package.json for it. A package.json may be included for the sake of specifying dependencies. Here's an example. We do not allow other fields, such as "description", to be defined manually. Also, if you need to reference an older version of typings, you must do that by adding "dependencies": { "@types/foo": "x.y.z" } to the package.json.

I notice some tsconfig.json are missing "noImplicitAny": true, "noImplicitThis": true, or "strictNullChecks": true.

Then they are wrong. You can help by submitting a pull request to fix them.

Can I request a definition?

Here are the currently requested definitions.

What about type definitions for the DOM?

If types are part of a web standard, they should be contributed to TSJS-lib-generator so that they can become part of the default lib.dom.d.ts.

A package uses export =, but I prefer to use default imports. Can I change export = to export default?

If default imports work in your environment, consider turning on the --allowSyntheticDefaultImports compiler option. Do not change the type definition if it is accurate. For an NPM package, export = is accurate if node -p 'require("foo")' is the export, and export default is accurate if node -p 'require("foo").default' is the export.

I want to use features from TypeScript 2.1.

Then you will have to add a comment to your definition header: // TypeScript Version: 2.1. If it is merged before January 7, it will be published as a prerelease version, such as 4.3.0-next.0.

License

This project is licensed under the MIT license.

Copyrights on the definition files are respective of each contributor listed at the beginning of each definition file.