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javascript - stopping form submit if the validation fails.

I am validating the dates in below function. If the validation fails, then the form should not get submitted. I tried returning false in form onsubmit but it still gets submitted. However, Validation is working fine and getting the alert that I put in the function. Any help to stop submitting the form if validation fails.

<script>
  function dateCheck()
  {
      start = document.getElementById('name3').value;
      end = document.getElementById('name4').value;
      compare(start, end);
      document.getElementById('name4').focus();

  }

  function compare(sDate, eDate)
  {

      function parseDate(input) {
            var parts = input.match(/(d+)/g);

            return new Date(parts[2], parts[0]-1, parts[1]); // months are 0-based
          }
       var parse_sDate = parseDate(sDate);
      var parse_eDate = parseDate(eDate);
       parse_sDate.setFullYear(parse_sDate.getFullYear() + 1);

      if(parse_eDate >= parse_sDate)
          {
          alert("End date should not be greater than one year from start date");
           return false;
          }
       return true;
  }

</script>
</head>
<body>
<form onsubmit="return dateCheck()">
<table>
<tr>
<td><input type="text" name="soname3" id="name3" size="15" readonly="readonly"> 
<img src="../Image/cal.gif" id="" style="cursor: pointer;" onclick="javascript:NewCssCal('name3','MMddyyyy','dropdown',false,'12')" /></td>
 <td><input type="text" name="soname4" id="name4" size="15" readonly="readonly">
 <img src="../Image/cal.gif" id="" style="cursor: pointer;" onclick="javascript:NewCssCal('name4','MMddyyyy','dropdown',false,'12'); " /> </td>
 </tr>
</table>
<input type="submit" value="Submit">
</form>
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1 Reply

0 votes
by (71.8m points)

Just a comment:

If your listener passes a reference to the form, you can access the controls by name or ID:

<form onsubmit="return dateCheck(this)">

then:

function dateCheck(form) {
  var start = form.name3.value;
  ...
}

Note that you should declare variables, otherwise they will become global at the point they are assigned to. Also, you should check the values in the controls before passing them to the compare function (and display a message asking the user to enter a valid value if they aren't).

function dateCheck(form) {
  var start = form.name3.value;
  var end = form.name4.value;
  var valid = compare(start, end);

  if (!valid) form.name4.focus();

  return false;
}

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