tslib
This is a runtime library for TypeScript that contains all of the TypeScript helper functions.
This library is primarily used by the --importHelpers flag in TypeScript.
When using --importHelpers, a module that uses helper functions like __extends and __assign in the following emitted file:
var __assign = (this && this.__assign), Object.assign, function(t) {
for (var s, i = 1, n = arguments.length; i < n; i++) {
s = arguments[i];
for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
t[p] = s[p];
}
return t;
};
exports.x = {};
exports.y = __assign({}, exports.x);
will instead be emitted as something like the following:
var tslib_1 = require("tslib");
exports.x = {};
exports.y = tslib_1.__assign({}, exports.x);
Because this can avoid duplicate declarations of things like __extends, __assign, etc., this means delivering users smaller files on average, as well as less runtime overhead.
For optimized bundles with TypeScript, you should absolutely consider using tslib and --importHelpers.
Installing
For the latest stable version, run:
npm
# TypeScript 2.3.3 or later
npm install --save tslib
# TypeScript 2.3.2 or earlier
npm install --save tslib@1.6.1
yarn
# TypeScript 2.3.3 or later
yarn add tslib
# TypeScript 2.3.2 or earlier
yarn add tslib@1.6.1
bower
# TypeScript 2.3.3 or later
bower install tslib
# TypeScript 2.3.2 or earlier
bower install tslib@1.6.1
JSPM
# TypeScript 2.3.3 or later
jspm install tslib
# TypeScript 2.3.2 or earlier
jspm install tslib@1.6.1
Usage
Set the importHelpers compiler option on the command line:
tsc --importHelpers file.ts
or in your tsconfig.json:
{
"compilerOptions": {
"importHelpers": true
}
}
For bower and JSPM users
You will need to add a paths mapping for tslib, e.g. For Bower users:
{
"compilerOptions": {
"module": "amd",
"importHelpers": true,
"baseUrl": "./",
"paths": {
"tslib" : ["bower_components/tslib/tslib.d.ts"]
}
}
}
For JSPM users:
{
"compilerOptions": {
"module": "system",
"importHelpers": true,
"baseUrl": "./",
"paths": {
"tslib" : ["jspm_packages/npm/tslib@1.10.0/tslib.d.ts"]
}
}
}
Contribute
There are many ways to contribute to TypeScript.
- Submit bugs and help us verify fixes as they are checked in.
- Review the source code changes.
- Engage with other TypeScript users and developers on StackOverflow.
- Join the #typescript discussion on Twitter.
- Contribute bug fixes.
- Read the language specification (docx, pdf).