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title: ECMAScript 6中的let和const关键词 categories:

• JavaScript
• 前端杂烩 tags:
• tech
• cnblogs
• ES6 warning: true date: 2013-11-28 09:46:00 fromUrl: http://www.cnblogs.com/hustskyking/archive/2013/11/28/ES6-computed-properties.html from: 博客园

var a = 5;
if(true){
    var a = 10;
}
console.log(a);//10

let a = 5;
if(true){
    let a = 10;
}
console.log(a); //5

const aa = 11;
alert(aa) //11
aa = 22;
alert(aa) //11

"use strict";
function fn() {
    const y = 0;
    for (let x = 0; x < 10; x++) {
        const y = x * 2;
        const z = y;
    }
    console.log(y); // prints 0
}
fn();

"use strict";
function fn() {
    var y = 0;
    for (var x = 0; x < 10; x++) {
        var y$0 = x * 2;
        var z = y$0;
    }
    console.log(y); // prints 0
}
fn();