<script type="text/javascript" > window.onload = function () { //定义这个setTimeout 就是1秒执行一次! setTimeout(Change, 1000); }; function Change() { var time = document.getElementById("time").innerHTML; time = parseInt(time); time--; if (time<1) { var url = document.getElementById("url").href; window.location.href = url; } else { document.getElementById("time").innerHTML = time; setTimeout(Change, 1000); } } </script>
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<body> <span style="font-size:28px;color: #ff0000" id="time">5</span><a id="url" href="Default.aspx"></a>
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</html>原文：http://www.cnblogs.com/crazyair/p/3638471.html