let
//声明变量
let a;
let b,c,d;
let e = 100;
let f = 521,g = 'iloveyou', h = [];
//1.变量不能重复声明
//let star = '罗志祥';
//let star = '小猪';
//2.块级作用域 全局，函数，eval
//if else while for
//{
// let girl = '周扬青';
//}
//3.不存在变量提升
//console.log(song);
//let song = '恋爱达人';
//4.不影响作用域链
{
let study = 'es6';
function fn(){
console.log(study);
}
fn();
}