JavaScript基础

switch

 <script language="javascript">
 
        var seson = prompt("请输入数字（1～4）");
        switch (seson) {
            case "1": msg = "你选择的春天"; break;
            case "2": msg = "你选择的夏天"; break;
            case "3": msg = "你选择的秋天"; break;
            case "4": msg = "你选择的冬天"; break;
            default: msg = "你选择的不对"; break;
        }
        document.write(msg);

    </script>

多个函数同时调用

<script language="javascript">
<!--
    function fun1(){
        alert("这是fun1");        
    }
    function fun2(){
        alert("这是fun2");
    }
//-->
</script>
</head>
<body>
<input type="button" value="单击我" onClick="fun1(),fun2()">
</body>

绝对值函数的应用

<script language="javascript">
<!--
    document.write("0的绝对值为：",Math.abs(0),"<br>");
    document.write("1的绝对值为：",Math.abs(1),"<br>");
    document.write("-1的绝对值为：",Math.abs(-1),"<br>");
//-->
</script>

try catch处理

<script language="javascript">
<!--
    try{
        a[1] = 10;
    }catch(e){
        alert("错误:"+e);
    }
-->
</script>

连接两个数组

<script language="javascript">
<!--
    a = new Array("a","b","c");
    b = new Array(1,2,3);
    c = a.concat(b);
    
    for(i=0;i<c.length;i++){
        document.write(c[i],"<br>");
    }
//-->
</script>

平方根函数的使用

<script language="javascript">
<!--
    n = prompt("请输入一个要平方根的数：");
    document.write(n,"的平方根为:",Math.sqrt(n));
//-->
</script>

得到一个数的平方

<script language="javascript">
<!--
    radius = prompt("请输入一个数：");
    area =Math.pow(radius, 2);
    document.write("这个数的平方是:" + area);
//-->
</script>

取得对象的信息

<body>
<script language="javascript">
<!--
    function showID(obj){
        alert(obj.id);
    }
//-->
</script>
<input type="button" value ="显示" id="bt" onClick="showID(this)">
</body>

取整函数的使用

<body>
<script language="javascript">
<!--
    n = prompt("请输入一个要取整的数：");
    if(n>0){
        int = Math.floor(n);
    }else{
        int = Math.ceil(n);
    }
    document.write(n,"的整数为:",int);
//-->
</script>
</body>

取得类别名称

<style type="text/css">
<!--
    .bgcolor{
        background-color:#993300;
}
-->
</style>
</head>
<body>
<input type="button" value ="显示" id="bt" onClick="alert
(bt.className)" class="bgcolor">
</body>