使用JS,使得加载页面之前显示GIF图片
下面是代码,这是伪加载提示条,跟加载速度无关
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title></title> <style type="text/css"> .current a { font-size: 20px; } .over { display: block; position: absolute; top: 250px; left: 0; width: 100%; height: 700px; background-color: white; opacity:0.5; z-index: 1000; } .layout { display: block; position: absolute; top: 20%; left: 20%; width: 20%; height: 20%; z-index: 1001; text-align:center; } </style> <script type="text/javascript"> setTimeout(showMain,"2700"); function showMain() { document.getElementById("over").style.display = "none"; document.getElementById("layout").style.display = "none"; } </script> </head> <body> <div class="current"><a href="#" onclick="showMain()">Loading</a></div> <div id="over" class="over"></div> <div id="layout" class="layout"><img src="loading.gif" /></div> </body> </html>
下面是网上其他人的解决方法,可以真正实现显示加载的百分比
如果需要在页面初始加载时显示加载进度。主要是指图片很多的情况下:
var imgNum = 0; var images = []; $(function(){ preloadImg(); }); //里面有两种方式 function preLoadImg() { //第一种方式:通过dom方法获取页面中的所有img,包括<img>标签和css中的background-image /*get all imgs those tag is <img> var imgs = document.images; for (var i = 0; i < imgs.length; i++) { images.push(imgs[i].src); } //get all images in style var cssImages = getallBgimages(); for (var j = 0; j < cssImages.length; j++) { images.push(cssImages[j]); }*/ //第二种方式:把所有该网页上用到的图片文件都预先放入一个数组里 $.imgpreload([‘images/bg1.jpg‘, ‘images/bg2.jpg‘], function () { //此处是显示进度百分比时需要用到的背景图,这个可以先加载进去 }); //then push all other images in array to load images.push("images/test_1.png"); images.push("images/test_2.png"); images.push("images/test_3.png"); //。。。 images.push("images/test_n.png"); /*这里是真正的图片预加载 preload*/ $.imgpreload(images, { each: function () { /*this will be called after each image loaded*/ var status = $(this).data(‘loaded‘) ? ‘success‘ : ‘error‘; if (status == "success") { var v = (parseFloat(++imgNum) / images.length).toFixed(2); $("#percentShow").html(Math.round(v * 100) + "<sup>%</sup>"); } }, all: function () { /*this will be called after all images loaded*/ $("#percentShow ").html("100<sup>%</sup>"); $("percentShow").fadeOut(1000); $(".main").show(); } }); } //get all images in style(此方法引用其他博客的) function getallBgimages() { var url, B = [], A = document.getElementsByTagName(‘*‘); A = B.slice.call(A, 0, A.length); while (A.length) { url = document.deepCss(A.shift(), ‘background-image‘); if (url) url = /url\([‘"]?([^")]+)/.exec(url) || []; url = url[1]; if (url && B.indexOf(url) == -1) B[B.length] = url; } return B; } document.deepCss = function (who, css) { if (!who || !who.style) return ‘‘; var sty = css.replace(/\-([a-z])/g, function (a, b) { return b.toUpperCase(); }); if (who.currentStyle) { return who.style[sty] || who.currentStyle[sty] || ‘‘; } var dv = document.defaultView || window; return who.style[sty] || dv.getComputedStyle(who, "").getPropertyValue(css) || ‘‘; } Array.prototype.indexOf = Array.prototype.indexOf || function (what, index) { index = index || 0; var L = this.length; while (index < L) { if (this[index] === what) return index; ++index; } return -1; }
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