<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>let</title> </head> <body> <script> //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. 块儿级作用域 全局, 函数, eval // if else while for // { // let girl = '周扬青'; // } // console.log(girl); //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 school = '尚硅谷'; function fn(){ console.log(school); } fn(); } </script> </body> </html>