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js图片延迟技术一般的思路与示例_javascript技巧

时间:2021-07-01 10:21:17 帮助过:4人阅读

图片延迟技术一般的思路

1.现将img元素对应的src路径设置为背景图片,而该img所对应的url路径存放在一个自设的属性中(以便进行src替换)。

2.获取卷轴的高度和窗口的高度

3循环需要延迟加载的img数组,获取img的高度,判断该元素是否在可视窗口内。若该元素在可视窗口内,则进行src替换

一下为测试代码

html
代码如下:






  • test

  • test

  • test




  • js部分
    代码如下:

    var imgsglobal=[
    "http://cdn.duitang.com/uploads/item/201306/07/20130607171626_QkC3T.thumb.600_0.jpeg",
    "http://img4.duitang.com/uploads/item/201306/07/20130607172438_Teijr.jpeg",
    "http://cdn.duitang.com/uploads/item/201306/08/20130608190311_BYwcA.thumb.600_0.jpeg",
    "http://g-ec4.images-amazon.com/images/G/28/BOOK-Catalog/Liaoxiaojun/B003U5TATY_01_AMZN.jpg",
    "http://www.yishun.net/tuysL3R1eXNpbWcwNC50YW9iYW9jZG4uY29tL2ltZ2V4dHJhL2k0Lzc0MDY1MDAzMi9UMl9HbmVYanRhWFhYWFhYWFhfISE3NDA2NTAwMzIuanBn.jpg",
    "http://www.yishun.net/tuysL3R1eXNpbWcwMy50YW9iYW9jZG4uY29tL2ltZ2V4dHJhL2kzLzc0MDY1MDAzMi9UMkVHbF9YaVhjWFhYWFhYWFhfISE3NDA2NTAwMzIuanBn.jpg",
    "https://img.gxlcms.com//Uploads-s/new/2019-09-24-201924/20130608190125_3kFty.jpeg",
    "http://img4.duitang.com/uploads/item/201304/29/20130429142901_SQjJv.thumb.600_0.jpeg",
    "http://img4.duitang.com/uploads/item/201112/04/20111204170801_fiBKm.jpg",
    "http://img2.duitang.com/uploads/item/201211/06/20121106233027_LdQaS.thumb.600_0.jpeg",
    "https://img.gxlcms.com//Uploads-s/new/2019-09-24-201924/U5238P115DT20110127111837.jpg",
    "http://img2.duitang.com/uploads/item/201209/24/20120924162953_hLPJe.jpeg",
    "http://wenwen.soso.com/p/20110624/20110624085901-745594320.jpg",
    "http://img4.duitang.com/uploads/item/201206/15/20120615185646_uzmrt.thumb.600_0.jpeg",
    "http://img4.duitang.com/uploads/item/201202/11/20120211213039_U4Sj8.thumb.600_0.jpg",
    "http://cdn.duitang.com/uploads/item/201201/25/20120125145922_n4Vz8.thumb.600_0.jpg"
    ];
    function addImgEle(){
    var str='';
    for(var i=0, len=imgsglobal.length; istr+='
  • '
    }
    $("#showImg").append(str);
    }
    $(document).ready(function(){
    addImgEle();
    });
    (function(win){
    var lazyLoad=win['lazyLoad']||{};
    var camelize = function (s) {
    return s.replace(/-(\w)/g, function (strMatch, p1) {
    return p1.toUpperCase();
    });
    };
    lazyLoad={
    init:function(ImgClass){
    var offsetPage = window.pageYOffset ? window.pageYOffset : window.document.documentElement.scrollTop,
    offsetWindow = offsetPage + Number(window.innerHeight ? window.innerHeight : document.documentElement.clientHeight);
    var Imgeles=ImgClass;
    for(var i=0, len=Imgeles.length; iif(Imgeles[i].getAttribute("resrc")=="show"){
    continue;
    }
    var o=Imgeles[i];
    if(o){
    postPage = o.getBoundingClientRect().top + window.document.documentElement.scrollTop +window.document.body.scrollTop;
    postWindow = postPage + Number(this.getStyle(o, 'height').replace('px', ''));
    if ((postPage > offsetPage && postPage < offsetWindow) || (postWindow > offsetPage && postWindow < offsetWindow)){
    var src=o.getAttribute("resrc");
    o.setAttribute("src", src);
    o.setAttribute("resrc", "show");
    }
    }
    }
    },
    getStyle:function (element, property) {
    if (arguments.length != 2) return false;
    var value = element.style[camelize(property)];
    if (!value) {
    if (document.defaultView && document.defaultView.getComputedStyle) {
    var css = document.defaultView.getComputedStyle(element, null);
    value = css ? css.getPropertyValue(property) : null;
    } else if (element.currentStyle) {
    value = element.currentStyle[camelize(property)];
    }
    }
    return value == 'auto' ? '' : value;
    }
    }
    win.lazyLoad=lazyLoad;
    })(window);
    $(document).ready(function(){
    lazyLoad.init($("img.lazyImg"));
    window.onscroll=function (){
    lazyLoad.init($("img.lazyImg"));
    }
    });

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