页面加载完成后执行JS代码

<script>
var ready = function(fun)
{
if (document.addEventListener)
{
document.addEventListener("DOMContentLoaded", fun, false);
}
else
{
var head = document.getElementsByTagName("head")[0];
var script = document.createElement("script");
script.src = "javascript:void(0)";
script.defer = true;
script.onreadystatechange = function()
{
if (this.readyState == "loaded" || this.readyState == "complete")
{
fun.apply(this, arguments);
head.removeChild(this);
}
}
head.appendChild(script);
}
}
</script>

ready(function()
{
alert("ok!");
});