###JS分支和循环

JS 分支和循环

  <script>
        'use strict'
        /*if判断*/
        var age = 3;
        if (age > 3) {//第一判断
            alert("大于3")
        } else if (age < 5) {//第二判断
            alert("小于5")
        } else {        //否则
            alert("其他")
        }

        /*while循环*/
        while (age < 7) {
            age = age + 1;
            console.log(age);
        }

        /*for循环*/
        for (let i = 0; i < 5; i++) {
            console.log(i)
        }

        /*for each遍历*/
        var num = ['a', 'b', 'c', 'd', 'e'];
        num.forEach(function (value) {
        console.log(value);
        });

        /*for in遍历，用的是下标*/
        //for (var index in object){}
        for (var index in num) {
            console.log(num[index])
        }
        /*for of*/
        for (let string of num) {
            console.log(string);
        }
        
    </script>