JS Loading功能的简单实现

我们经常在浏览网页的时候会看到数据在加载时，出现的LOADING提示。其实这个功能原理是很简单的，就是一个DIV遮盖当前页面，然后Loading就在遮盖DIV层上展示出来，现在我们来动手实现一下。

1.当前页面：


代码如下:

<div class="current"><a href="#" onclick="showLoading()">Loading</a></div>

2.遮罩层：


代码如下:

<div id="over" class="over"></div>

3.Loading展示层：


代码如下:

<div id="layout" class="layout"><img src="http://zsrimg.ikafan.com/file_images/article/201311/2013112931.gif" alt="" /></div>

整体代码:


代码如下:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
    <style type="text/css">
        .current a {
            font-size: 20px;
        }

.over {
            display: none;
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: #f5f5f5;
            opacity:0.5;
            z-index: 1000;
        }

.layout {
            display: none;
            position: absolute;
            top: 40%;
            left: 40%;
            width: 20%;
            height: 20%;
            z-index: 1001;
            text-align:center;
        }
    </style>
    <script type="text/javascript">
        function showLoading()
        {
            document.getElementById("over").style.display = "block";
            document.getElementById("layout").style.display = "block";
        }
    </script>
</head>
<body>
    <div class="current"><a href="#" onclick="showLoading()">Loading</a></div>
    <div id="over" class="over"></div>
    <div id="layout" class="layout"><img src="http://zsrimg.ikafan.com/file_images/article/201311/2013112931.gif" alt="" /></div>
</body>
</html>

最终效果：

在网上还看到另外一种实现方式，感觉思路不错，就是利用JS不断的改变html标签的value值，达到加载提示的效果，根据他的思路我自己实现了下，代码如下：


代码如下:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
    <!-- <script src="Scripts/jquery-1.8.2.js"></script>-->
    <style type="text/css">
        #tb {
            width: 100%;
            height: 100%;
            line-height: 10px;
        }

#tb tr td {
                text-align: center;
            }

.progressbar {
            font-family: Arial;
            font-weight: bolder;
            color: gray;
            background-color: white;
            padding: 0px;
            border-style: none;
        }

.percent {
            font-family: Arial;
            color: gray;
            text-align: center;
            border-width: medium;
            border-style: none;
        }
    </style>
    <script type="text/javascript">
        var bar = 0;
        var step = "||";
        /*
        *第一种方式即 ：$(document).ready(function(){.....});
        */
        //$(function () {
        //    progress();
        //});

/*
        *第二种方式
        */
        //window.onload = function () {
        //    progress();
        //}

/*
        *第三种方式模拟 $(document).ready(function(){.....});
        */
        (function () {
            var ie = !!(window.attachEvent && !window.opera);
            var wk = /webkit\/(\d+)/i.test(navigator.userAgent) && (RegExp.$1 < 525);
            var fn = [];
            var run = function () { for (var i = 0; i < fn.length; i++) fn[i](); };
            var d = document;
            d.ready = function (f) {
                if (!ie && !wk && d.addEventListener)
                    return d.addEventListener('DOMContentLoaded', f, false);
                if (fn.push(f) > 1) return;
                if (ie)
                    (function () {
                        try { d.documentElement.doScroll('left'); run(); }
                        catch (err) { setTimeout(arguments.callee, 0); }
                    })();
                else if (wk)
                    var t = setInterval(function () {
                        if (/^(loaded|complete)$/.test(d.readyState))
                            clearInterval(t), run();
                    }, 0);
            };
        })();

document.ready(function () {

progress();

});

function progress() {
            bar = bar + 2;
            step = step + "||";
            document.getElementById("percent").value = bar + "%";
            document.getElementById("progressbar").value = step;
            if (bar <= 98) {
                setTimeout("progress()", 100);
            }
        }
    </script>
</head>
<body>
    <table id="tb">
        <tr>
            <td>
                <input type="text" size="50" class="percent" id="percent" /></td>
        </tr>
        <tr>
            <td>
                <input type="text" size="50" class="progressbar" id="progressbar" /></td>
        </tr>
    </table>
</body>
</html>

最终效果：