用js提交表单,没有submit按钮如何验证,使用button提交方法

 <script language="javascript">
    //表单提交
    function submit1(obj){
        obj.submit();
    }
    </script>

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_____________________________________________onclick事件调用方法___________________________________________________________________________________

1. <form id="form1" name="form1" method="post" action="mzwucom.asp">  
2.       UserNmae:  
3.       <input name="username" type="text" id="username" size="10" maxlength="10" />  
4.       <input type="button" name="Submit" value="提交" onclick="submit1(this.form);" />  
5.     </form>