SOURCE

console 命令行工具 X clear

                    
>
console
localStorage.setItem('show', null)
console.log(localStorage.show||'123')
console.log(typeof localStorage.show)
console.log(null||'123123')
console.log(undefined||'123123')

console.log(func())
function func(){
    console.log(bar);
    return bar();
    // var bar=function(){return 5;};
    // var bar=()=>6;
    // var bar=(function(){return 7})();
    function bar(){return 8}
}

// console.log(bar)
// var bar = 0;

var a=0;
function sth(){
    var a=1;
    // function change(){
    //     a=2;
    //     return a;
    // }
    // return change();
    return a;
}
console.log(a, sth());
<div class='box'></div>
.box{
    width: 220px;
    height: 220px;
    padding: 20px;
    border: 20px solid black;
    margin: 20px;
    background: red;
    box-sizing: border-box;
}