1-5 流程控制语句

1.遍历对象

//遍历属性{
        for(var p in profile){
            console.log(p+':'+profile[p])
        }

2.遍历数组

       var fruits =['香蕉','苹果','雪梨','火龙果',]        
         for(i=0; i<fruits.length;i++){
             console.log(fruits[i])
             document.write(fruits[i])
        }

3.if else

var a  = 2
        console.log(a)
        if(a>3){
            console.log('a>3')
        }else{
            console.log('a<=3')
        }

4.switch

 //只有等于的时候才能用
        switch(floor){
            case 1:
            alert('上一楼');
             break;
            default:
            alert('请输入楼层')
        }