ES6-let变量声明以及特点

声明变量

let a;
let b,x,d;
let e = 100;
let f = 2000,g = "iloveyou".h = [];

1.let不能重复声明变量

let star = "Jay";
let star = "周杰伦"//报错
//var可以重复声明变量
var singer = "Jay";
var singer = "周杰伦"

2.块级作用域 全局，函数，eval

//if else while for
{
let girl = "昆凌"
}
console.log(girl);//报错

3.不存在变量提升

console.log(song);
let song = "恋爱达人"//报错

4.不影响作用域链

{
    let school = "清华大学"
    function fn(){
        console.log(school);
    }
    fn();
}

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