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tslib

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

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@1.8.1/tslib.d.ts"]
        }
    }
}

Contribute

There are many ways to contribute to TypeScript.

Documentation