按钮提交倒计时实现

var secs = 9;
var wait = secs * 1000;
/*其中licenseform为提交表单即<form name="licenseform">...</form>，
  其中btnSubmit为按钮submit的name值即<input type="button" name="btnSubmit"/>*/
document.licenseform.btnSubmit.value = "我同意 [" + secs + "]";
document.licenseform.btnSubmit.disabled = true;
for(i = 1; i <= secs; i++){
	window.setTimeout("Update(" + i + ")", i * 1000);
}
//
window.setTimeout("Timer()", wait);

function Update(num){
	if(num != secs)	{
		printnr = (wait / 1000) - num;
		document.licenseform.btnSubmit.value = "我同意 [" + printnr + "]";
	}
}

function Timer(){
	document.licenseform.btnSubmit.disabled = false;
	document.licenseform.btnSubmit.value = " 我同意 ";
}