js验证表单文本框不能输入中文的方法

<script>
function chkIt(frm){
  if (frm.n1.value.length>0&&frm.n1.value.match(/[\x01-\xFF]*/)==false){
    alert('n1不能输入中文！')
    frm.n1.focus();
    return false;
  }
}
</script>
<body>
<form onsubmit="return chkIt(this)">
<input name="n1">
<input name="n2">
<input name="smt" type="submit" value="提交">
</form>
</body>

<input onpaste="return false;" type="text" name="textfield" style="width:400px; ime-mode:disabled" value="">

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