window.onload想必大家都有使用过吧，在窗口加载时执行，如果多次使用window.onload该如何判断呢？看看下面的代码

<script>function onloadCallback(){//Todo}if (window.onload) {var onload_random = 'onload'+Math.random();window[onload_random] = window.onload;window.onload = function (){window[onload_random]();onloadCallback();};}else {window.onload = function (){onloadCallback();};}</script>