 
<html> 
<head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"></head> 
<body style="background:#a7a7a7;"> 
<iframe id="testiframe" name="testiframe"></iframe> 
<form method="post" action="http://www.test.com/testaction.php" target="testiframe" name="testform"> 
<input type="text" name="dddd"><input type="submit" value="ddd" name="submitbtn"/> 
</form> 
</body> 
<script> 
document.testform.onsubmit = function () { 
document.testform.submitbtn.disabled = true; 
submitMonitor(); 

} 
function submitMonitor () { 
try{ 
var hash = document.getElementById('testiframe').contentWindow.location.hash; 
setTimeout(submitMonitor,100); 
} catch (e) { 
document.getElementById('testiframe').src = "about:blank"; 
document.testform.submitbtn.disabled = false; 
} 
} 
</script> 
</html> 

注意下面的代碼是跨域的，不是在一個域名下的
testaction.php

復(fù)制代碼代碼如下:

 
<?php 
sleep(5); 
echo $_POST['dddd']; 
?> 

弊端：
這個弊端還很明顯，如果是404，403，500等錯誤，也會誤認(rèn)為是成功提交。
所以，請注意：此方法屬研究，開拓思維用。
這段是百度的判斷代碼

復(fù)制代碼代碼如下:

var sfMessTimes; 
function sfMessSubmitMonitor () { 
try{ 
var hash = sf_mess_lib.getElement(SF_MESS_FRAME_ID).contentWindow.location.hash; 
        sfMessTimes ++; 
        if (sfMessTimes > 50) { 
            alert(sf_mess_msg.fail); 
            sf_mess_lib.getElement(SF_MESS_SUBMIT_ID).disabled = false; 
            for (var i = 0, l = sf_mess_cols.length; i < l; i++) { 
                document.getElementById(SF_MESS_PREFIX + sf_mess_cols[i].idname).disabled = false; 
            } 
        } else { 
            setTimeout(sfMessSubmitMonitor,100); 
        } 
} catch (e) { 
sf_mess_lib.getElement(SF_MESS_FRAME_ID).src = "about:blank"; 
        alert(sf_mess_msg.success); 
sf_mess_lib.getElement(SF_MESS_SUBMIT_ID).disabled = false; 
        for (var i = 0, l = sf_mess_cols.length; i < l; i++) { 
            var inputCfg = sf_mess_cols[i]; 
            var inputEl = document.getElementById(SF_MESS_PREFIX + inputCfg.idname); 
            inputEl.disabled = false; 
            inputEl.value = filtInnertip(inputCfg.innertip); 
        } 
} 
}