<script>
function checkSub() {
var isOK=false;
return isOK;
}
</script>
<body>
<form onsubmit="return checkSub()" action="checked.html">
<input type="submit">
</form>
</body>这时点击提交按钮是不可以提交表单的
<form onsubmit="checkSub()" action="checked.html">
<input type="submit">
</form>