Introduction, installation and use of core JS

Preface

Let me tell you something here core-js The developer of the , It is also the information consulted on the Internet .

core-js The author of ： A tough Russian programmer , Name is Dennis · Pushkarev （Denis Pushkarev）, My hobby is racing motorcycles .

And in an accident , He is in 60 km/h Driving at a speed of , As a result, he hit two pedestrians , One person died at the scene . According to the law of the Russian Federation , He was sentenced to fixed-term imprisonment 18 Months , deprive 2 Annual driving rights , In addition, a fine shall be imposed 138 All the ruble . 

Details address ：core-js Author jailed 18 Months ,2600 How to proceed with the open source project downloaded ten thousand times a week ？ - IT The home of When the programmer in charge of maintenance went to prison , Who will continue to maintain this self written JavaScript Standard library https://www.ithome.com/0/480/137.htm

One 、core-js What is it ？

1.  ECMAScript  The rapid growth of and the frequent updating of browsers , Every year, new api , for instance es6 The birth of the period   'Promise'  ,'Set'  Or is it 'es7'  Array provides new methods 'includes' , These newly added 'api' , Just one word "polyfill"  'polyfill( shim / Patch )' Is to use a piece of code provided by the community , Let's work on browsers that are not compatible with some new features , Use this new feature . New features es'api' Convert to one that most modern browsers can support 'api' Patch Collection .

2. Because the official library describes him
 2.1. It supports the latest ECMAScript standard
 2.2. It supports ECMAScript Standard library proposal
 2.3. It supports some WHATWG / W3C standard （ Cross platform or ECMAScript relevant ）
 2.4. It is modular to the maximum extent ： You can just load the functions you want to use
 2.5. It does not pollute the global namespace
 2.6. It and babel Tight integration ： This can optimize core-js Import of
 2.7. It is the most common 、 Most popular To JavaScript How to patch the standard library

Two 、core-js Related function packages .

Details address ：https://github.com/zloirock/core-js/tree/master/packageshttps://github.com/zloirock/core-js/tree/master/packages

stay 'corejs' Of the project packages In file in 'https://github.com/zloirock/core-js/tree/master/packages', You can see five related packages
  1.1.  'core-js' install 'npm install core-js' effect ' Defining the global polyfill'

  1.2. 'core-js-pure' install 'npm i core-js-pure' effect ' Provide the environment without pollution polyfill, Equivalent to [email protected]/library'

  1.3. 'core-js-compat' install 'npm i core-js-compat' Function maintained according to 'browserslist' Standard gasket requirement data , To help us find ' In line with the target environment ' Of 'polyfills' Demand set

  1.4. 'core-js-builder' install 'npm i core-js-builder' The effect can be Node.js Service usage , Build shim packs for different scenarios .

  1.5.'core-js-builder' install 'npm i core-js-builder' Action can be combined with 'core-js-compact' as well as 'core-js', And make use of 'webpack ' Ability ,  Package according to the demand core-js Code

3、 ... and 、 How to use ？

1.  install   npm The way

// global version
npm install --save [email protected]
// version without global namespace pollution
npm install --save [email protected]
// bundled global version
npm install --save [email protected]

2.  On demand import or global import

//  Import all new proposals api
import "core-js";
//  Only stable 'core js' function -es and web standard 
import "core-js/stable";
//  Only stable ES function 
import "core-js/es";
//  Import only specified api
import "core-js/features/set";

import "core-js/stable/set";
import "core-js/es/set";

3.  Use demo 

Mainly because IE The browser is not compatible with the new syntax 、api, So we need to use core-js Do compatibility processing , To solve the problem .

// first file:
import 'core-js/modules/es.array.iterator';
import 'core-js/modules/es.object.to-string';
import 'core-js/modules/es.set';
var set = new Set([1, 2, 3]);

// second file:
import 'core-js/modules/es.array.of';
var array = Array.of(1, 2, 3);

  For more details, you can go to GitHub Reference resources ： The address is just above