ASP Form Validation, disallow HTML

Posted on 2009-02-12
Medium Priority
Last Modified: 2012-05-06
I have a contactform in ASP which will sent the input to my email and a cc to the users email. There is a memo field in the form, I like to disallow users to use HTML and other scripts. We receive a lot of spam!

Is there a way to rebuild the following code? The name of the memofield is email_memo

Thanks for the response!
<script language="javascript" type="text/javascript">
document.oncontextmenu = function(){return false};
function MM_validateForm() { //v4.0
  if (document.getElementById){
    var i,p,q,nm,test,num,min,max,errors='',args=MM_validateForm.arguments;
    for (i=0; i<(args.length-2); i+=3) { test=args[i+2]; val=document.getElementById(args[i]);
      if (val) { nm=val.name; if ((val=val.value)!="") {
        if (test.indexOf('isEmail')!=-1) { p=val.indexOf('@');
          if (p<1 || p==(val.length-1)) errors+='- '+nm+' must contain an e-mail address.\n';
        } else if (test!='R') { num = parseFloat(val);
          if (isNaN(val)) errors+='- '+nm+' must contain a number.\n';
          if (test.indexOf('inRange') != -1) { p=test.indexOf(':');
            min=test.substring(8,p); max=test.substring(p+1);
            if (num<min || max<num) errors+='- '+nm+' must contain a number between '+min+' and '+max+'.\n';
      } } } else if (test.charAt(0) == 'R') errors += '- '+nm+' is een verplicht veld!.\n'; }
    } if (errors) alert('Er is iets mis gegaan:\n'+errors);
    document.MM_returnValue = (errors == '');
} }

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Question by:hanskoens
LVL 16

Accepted Solution

sunithnair earned 375 total points
ID: 23620339
Try this javascript. I would recomnend removing HTML tags using ASP as well or use Server.HTMLEncode to encode the string before sending the email. Javascript can be disabled in the browser in which case the validation will not work
<script language='javascript'>
var regEx=new RegExp("^(?!<[^>]*>).*$");
function CheckHtml()
<textarea id="txtBox"></textarea>
<input type="button" onclick="CheckHtml()" value="Test" />

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LVL 12

Expert Comment

ID: 23621603
The attached function might be useful for your ASP side.   Simply call the function to remove all HTML and SCRIPT from the variable like below.

Function stripHTML(strHTML)
  'Convert <BR> to crlf
  strHTML=Replace(strHTML, "<br>", vbcrlf)
  strHTML=Replace(strHTML, "<BR>", vbcrlf)
  strHTML=Replace(strHTML, "<p>", vbcrlf)
  strHTML=Replace(strHTML, "<P>", vbcrlf)
  'Strips the HTML tags from strHTML
  Dim objRegExp, strOutput
  Set objRegExp = New Regexp
  objRegExp.IgnoreCase = True
  objRegExp.Global = True
  objRegExp.Pattern = "<(.|\n)+?>"
  'Replace all HTML tag matches with the empty string
  strOutput = objRegExp.Replace(strHTML, "")
  'Replace all < and > 
  strOutput = Replace(strOutput, "<", "")
  strOutput = Replace(strOutput, ">", "")
  stripHTML = strOutput    'Return the value of strOutput
  Set objRegExp = Nothing
  stripHTML = replace(stripHTML, "&nbsp;", " ")
End Function

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