focus（）不能用我的html格式

Question

我不知道它是如何在片段中工作的！ :( 我检查了很多次。在我的输出中，即使电话号码错误，密码字段也会聚焦。

＆＃13;

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function checkmatch() {
  var name = $("#username").val();
  var address = $("#address").val();
  var email = $("#emailid").val();
  var mobile = $("#phonenum").val();
  var password = $("#newPwd").val();
  var cnfirmPassword = $("#confirmPwd").val();

  if (password != cnfirmPassword) {
    alert("Passwords do not match.");
    $("#newPwd").val('').focus();
    $("#confirmPwd").val('');
    return false;
  } else if ((name == null || name == "") || (address == null || address == "") || (email == null || email == "") || (mobile = null || mobile == "") || (password == null || password == "") || (cnfirmPassword == null || cnfirmPassword == "")) {
    alert("Please fill all the required fields.");
    return false;
  } else {
    /*$.ajax(
    	{
    		type: "POST",
    		url: "assmt1.php",
    		datatype: "html",
    		data:  $("#fm1").serialize(),
    		success: function(response)
    		{
    			
    		}
    	});
    alert("Your form has been submitted. Thank you!");*/
  }
}

function validateMobile() {
  var phoneno = $('#phonenum').val();
  var phone = document.forms["fm1"]["field4"].value;
  var phonenumber = phone.replace(/[^\d]+/g, "");
  if (phonenumber.length > 9 && phonenumber.length < 13) {
    return true;
  } else {
    alert("Enter a valid phone number");
    $("#phonenum").val('').focus();
    return false;
  }
}

function isnumberKey(evt) {
  var charCode = (evt.which) ? evt.which : evt.keyCode;
  if ((charCode > 31 && charCode < 43) || (charCode > 43 && charCode < 48) || (charCode > 57))
    return false;
  return true;
}

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form id="fm1" name="myForm" method="post">
  <label>Mobile Number <input  type="text" id = "phonenum" name="field4" onkeypress="return isnumberKey(event);" onchange = "validateMobile();" /></label>
  <label>Password <input type="password" id="newPwd" name="field5" /></label>
  <label>Confirm Password <input type="password" id="confirmPwd" name="field6"/>  </label>
  <input style="cursor:pointer" type="button" value="Submit" onclick="checkmatch();" name="Sign Up" />

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这是我的电话号码验证代码。我希望清除phonenumber字段，然后在验证失败时聚焦。

if (phonenumber.length > 9 && phonenumber.length < 13) {
  return true;
} else {
  alert("Enter a valid phone number");
  $("#phonenum").val('').focus();
  return false;
}