定义

 ECMAScript是欧洲计算机制造商协会，以JavaScript为基础制定的一种脚本语言标准。

优势

1.语法糖

比如箭头函数，解决了this的指向问题

2.工程优势

2.1 模块化

引入了import和export

暴露出单个变量

a.jsexport let a = "js"
b.jsimport { a } from "./a.js"console.log(a) //js	

暴露出多个变量

a.jslet myName = "lqz"let myAge = "24"export {myName,myAge}
b.jsimport {myName,myAge} from "./a.js"console.log(myName,myAge)  //lqz,24
-------------------------------------------
//也可以使用别名
a.jslet myName = "lqz"let sayName = function(){return `myName is ${myName}`}export {myName as name,sayName as sayHi}
b.jsimport {name,sayHi} from "./a.js"console.log(name) //lqzconsole.log(sayHi()) //myName is lqz
-------------------------------------------
//也可以导入整个模块
b.jsimport * as obj from "./a.js"console.log(obj.name)  //lqzconsole.log(obj.sayHi()) //myName is lqz

默认暴露 default

//一个js模块只能有一个默认导出
a.jsexport default {name:"lqz",sayHi(){return this.name}}
b.jsimport a from "./a.js"console.log(a.name)  //lqzconsole.log(a.sayHi())  //lqz

混合导入

a.jsexport defalut {sayHi(){return "Hi"}}export let myName = "lqz"
b.jsimport a,{ myName } from "./a.js"console.log(a.sayHi())   //Hi

2.2 模块化与组件化结合

2.3 内存安全