let var const 区别是什么

举个例子

var name = 'T-mac'

while (true) {
    var name = 'KOBE'
    console.log(name)  //KOBE
    break
}

console.log(name)  //KOBE

let name = 'T-mac'

while (true) {
    let name = 'KOBE'
    console.log(name)  //KOBE
    break
}

console.log(name)  //T-mac

let是块记作用域 var 全局作用域 const 修饰是常量。

引用网址
https://www.jianshu.com/p/b65e1a92d597