流程控制

if判断

 'use strict';
    let age = 3;
    if (age<3){//第一个判断
        alert("kuwa");
    }else if(age=5){//第二个判断
        alert("5");
    } else{//否则
        alert("hhh");
    }

while循环，避免程序死循环

while(age<100){
        age = age + 1;
        console.log(age);
    }
do{
        age = age + 1;
        console.log(age);
    }while(age<100);

for循环

for (let i = 0; i < 100; i++) {
        console.log(age);
    }

forEach循环

let arr = [16,46,14,43,78,9,40,11,4];
    //函数
    arr.forEach(function (value){
        console.log(value);
    });

for...in

    /*
    *for(Type str:el){}
    * */
    //for(var index in object)
    for(let num in arr){
        if (arr.hasOwnProperty(num)){
            console.log("存在");
            console.log(arr[num]);
        }
    }