Conditional Validaton with Javascript

While I try to stay away from javascript validation, sometimes security concerns get trumped by "quick and dirty."  Such is the case when you need simple, conditional validation on forms in SharePoint.  Logic like "if Due Date is not NULL then make Justification required."  This was the example used in the question from STP today. 

As usual, I was onto the solution when someone’s blog straight up answered it for me.  Thanks to Edin Kapic for posting his date logic soluton.  So far this only works while the "Justification" field is a Plain text field.  I had too much trouble getting the RTF field to properly identify any attributes I could use the logic portion.  If someone else can get it to work with an RTF field, please drop me a line or post on EndUserSharePoint.com.

<script type="text/javascript">

 

function PreSaveAction()

{

    var findDate = getTagFromIdentifierAndTitle("input","DateTimeFieldDate","Due Date");

    var findText = getTagFromIdentifierAndTitle("textarea","","Test");

    if(findDate.value != "" && findText.value == "")

    {

        alert("You must provide a Justification for the Due Date");

        return false; // Cancel the item save process

    }

    return true;  // OK to proceed with the save item

}

 

function getTagFromIdentifierAndTitle(tagName, identifier, title) {

  var len = identifier.length;

  var tags = document.getElementsByTagName(tagName);

  for (var i=0; i < tags.length; i++) {

    var tempString = tags[i].id;

    if (tags[i].title == title && (identifier == "" || tempString.indexOf(identifier) == tempString.length – len)) {

      return tags[i];

    }

  }

  return null;

}

//–>

</script>