JQuery for与each性能比较分析

话不多说，直接上demo：

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>JQuery for与each性能比较分析</title>
</head>
<body>
<form id="form1" runat="server">
    <div><select id="select_test">
        <option value='1'>111111</option>
        <option value='2'>222222</option>
        <option value='3'>333333</option>
        <option value='4'>444444</option>
        <option value='5'>5</option>
        <option value='6'>6</option>
        <option value='7'>7</option>
        <option value='8'>8</option>
        <option value='9'>9</option>
        <option value='10'>10</option>
        <option value='11'>11</option>
        <option value='12'>12</option>
        <option value='13'>13</option>
        <option value='14'>14</option>
        <option value='15'>15</option>
        <option value='16'>16</option>
        <option value='17'>17</option>
        <option value='18'>18</option>
        <option value='19'>19</option>
        <option value='20'>20</option>
    </select><input type="button" value="开始比较" onclick="getSelectLength();"/></div>
</form>
</body>
<script src="jquery-1.8.1.min.js"></script>
<script type="text/javascript" language="javascript">
    function getSelectLength() {
        var time1 = new Date().getTime();
        var len = $("#select_test").find("option").length;
        var selectObj = $("#select_test");
        for (var i = 0; i < len; i++) {
            if (selectObj.get(0).options[i].text == "111111") {
                selectObj.get(0).options[i].selected = true;
                break;
            }
        }
        var time2 = new Date().getTime();
        alert("for循环执行时间：" + (time2 - time1));
        time1 = new Date().getTime();
        $("#select_test").find("option").each(function () {
            if ($(this).text() == "111111") {
                $(this)[0].selected = true;
            }
        });
        time2 = new Date().getTime();
        alert("each循环执行时间：" + (time2 - time1));
    }
</script>
</html>

　　输出： 
　　　　for循环执行时间：1 
　　　　each循环执行时间：3 

 

如果不够明显，可以多copy一些option

posted @ 2017-07-01 12:55  likwin  阅读(361)  评论(0)  编辑  收藏  举报