JavaScript_9

JavaScript_9_循环

1. JavaScript for/in 语句循环遍历对象的属性：

可以遍历数组，也可以遍历一个对象的所有属性

<body>

    <p>点击按钮，循环遍历对象“person”的属性</p>
    <button onclick="myfunction()">点击这里</button>
    <p id="d1"></p>
    <script>
        function myfunction()
        {
            var txt = "";
            var person = { firstname: "yoyo", lastname: "xiao", age: 34 };
            for(x in person)
            {
                txt = txt + person[x];//把属性的值都转入一个数组
            }
            document.getElementById("d1").innerHTML = txt;
        }
    </script>

    <script>
        var cars = ["Audi", "BMW", "Saab","Ford"];
        for (x in cars)
        {
            document.write(cars[x]+"</br>");
        }
    </script>

</body>

2. For循环

for (语句 1; 语句 2; 语句 3) { 被执行的代码块 }

3. While循环

while(condition)

{

代码块

}

{

} while(condition)

4. break: 跳出循环

continue: 跳出当次循环