<form method="post" id="myform" action="a.php">
<input type="submit" value="提交表单">
</form>

<script type="text/javascript">
function validate(){
 document.getElementByIdx_x('myform').submit();
}
window.load=validate();
</script>

<form method="post" id="myform" action="a.php">
<input type="test" value="name"/>
</form>
<a href="javascript:validate()">提交</a>

<script type="text/javascript">
function validate(){
 document.getElementByIdx_x('myform').submit();
}
</script>