详解如何使用babel进行es6文件的编译

npm i babel-cli -g 

let num = [1,2,3,4]; 
let plusDouble = num.map(item => item * 2); 
console.log(plusDouble); 

babel es6.js -o compiled.js 

{ 
 "presets": [], 
 "plugins": [] 
} 

npm i --save-dev babel-preset-es2015 

{ 
 "presets": ["es2015"], 
 "plugins": [] 
} 

"use strict";  
var num = [1, 2, 3, 4]; 
var plusDouble = num.map(function (item) { 
 return item * 2; 
}); 
console.log(plusDouble); 

npm i babel-plugin-transform-object-rest-spread --save-dev 

{ 
 "presets": ["es2015"], 
 "plugins": ["transform-object-rest-spread"] 
} 

let courses = { name: 'english', score: 90}; 
courses = { ...courses, comment: 'A'}; 
console.log(courses); 

'use strict';  
var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };  
var courses = { name: 'english', score: 90 }; 
courses = _extends({}, courses, { comment: 'A' }); 
console.log(courses);