TSDocTypeScript includes a default set of type definitions for built-in JS APIs (like Math), as well as type definitions for things found in browser environments (like document). TypeScript also includes APIs for newer JS features matching the target you specify; for example the definition for Map is available if target is ES6 or newer.
You may want to change these for a few reasons:
- Your program doesn't run in a browser, so you don't want the
"dom"type definitions - Your runtime platform provides certain JavaScript API objects (maybe through polyfills), but doesn't yet support the full syntax of a given ECMAScript version
- You have polyfills or native implementations for some, but not all, of a higher level ECMAScript version
In TypeScript 4.5, lib files can be overriden by npm modules, find out more in the blog.
High Level libraries
| Name | Contents |
|---|---|
ES5 | Core definitions for all ES3 and ES5 functionality |
ES2015 | Additional APIs available in ES2015 (also known as ES6) - array.find, Promise, Proxy, Symbol, Map, Set, Reflect, etc. |
ES6 | Alias for "ES2015" |
ES2016 | Additional APIs available in ES2016 - array.include, etc. |
ES7 | Alias for "ES2016" |
ES2017 | Additional APIs available in ES2017 - Object.entries, Object.values, Atomics, SharedArrayBuffer, date.formatToParts, typed arrays, etc. |
ES2018 | Additional APIs available in ES2018 - async iterables, promise.finally, Intl.PluralRules, regexp.groups, etc. |
ES2019 | Additional APIs available in ES2019 - array.flat, array.flatMap, Object.fromEntries, string.trimStart, string.trimEnd, etc. |
ES2020 | Additional APIs available in ES2020 - string.matchAll, etc. |
ES2021 | Additional APIs available in ES2021 - promise.any, string.replaceAll etc. |
ESNext | Additional APIs available in ESNext - This changes as the JavaScript specification evolves |
DOM | DOM definitions - window, document, etc. |
WebWorker | APIs available in WebWorker contexts |
ScriptHost | APIs for the Windows Script Hosting System |
Individual library components
| Name |
|---|
DOM.Iterable |
ES2015.Core |
ES2015.Collection |
ES2015.Generator |
ES2015.Iterable |
ES2015.Promise |
ES2015.Proxy |
ES2015.Reflect |
ES2015.Symbol |
ES2015.Symbol.WellKnown |
ES2016.Array.Include |
ES2017.object |
ES2017.Intl |
ES2017.SharedMemory |
ES2017.String |
ES2017.TypedArrays |
ES2018.Intl |
ES2018.Promise |
ES2018.RegExp |
ES2019.Array |
ES2019.Object |
ES2019.String |
ES2019.Symbol |
ES2020.String |
ES2020.Symbol.wellknown |
ES2021.Promise |
ES2021.String |
ES2021.Weakref |
ESNext.AsyncIterable |
ESNext.Array |
ESNext.Intl |
ESNext.Symbol |
This list may be out of date, you can see the full list in the TypeScript source code.