原生javascript图片惰性延迟加载–兼容PC端手机端

/**
 * 名称:xmanLazyLoad
 * 功能:网页图片惰性加载,兼容各浏览器
 * 用法: 使用方法:
    1.加载JS
        <script type="text/javascript" src="lazy_load.js" ></script>
    2.设置IMG属性
        <img src="http://placehold.it/90x90"  class="xLazyClass" xLazyImg="http://image.game.uc.cn/2014/2/17/9631225.jpg" alt="仙剑奇缘"/>
    API
    1.设置class
    需要惰性加载的图片class="xLazyClass"
    2.设置图片真实路径
    xLazyImg="http://image.game.uc.cn/2014/2/17/9631225.jpg"
    3.设置图片假路径
    src="http://placehold.it/90x90"
 * @author luozx
 * @Email [email protected]
 * @version 1.0.0
 * @dependencies none
 */
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