Prevent URLs from being entered into form fields?

[TeamKaeru]

Hi, I'm already doing validation of form fields for an .asp form - was wondering if anyone out there had any quickie code that they like to use in order to prevent a web user from entering a URL string / web link into a form field.

Was looking at something along the lines of this Javascript, but I'm not sure that would be sufficient.

<Script language = "Javascript">
function isIllegalChars(){
var s = document.forms['contactform'].elements['message'].value;
if (( s.search("URL") >= 0) || ( s.search("http") >= 0)) {
alert ("stop putting URLs in the form fields!");
return false;
}
return true;
}
</Script>

[Sayonara]

I would not use javascript - if someone wants to get around your code, they can just turn JS off.

Have the script that handles the form submission remove invalid content.

[TeamKaeru]

Yep, I'm lookin' for some code that people might already be using, the javascript provided in example was just an idea of what I was looking for.

[graficus]

Maybe you can use this as a starting point:


function CleanChars(strWords)
dim badChars,i
dim newChars

newchars=strwords

if len(Strwords)<15 then
cleanChars = newChars
exit function
end if

badChars = array("select", "drop", ";", "--", "insert", "delete", "xp_","union","char","@@")
newChars = strWords

for i = 0 to uBound(badChars)
if instr(1,newchars,badchars(i),1)>0 then
newchars=""
cleanchars=newchars
exit function
end if
next

newchars=replace(newchars,"'","''")
cleanChars = newChars
end function%>


This code makes sure no "bad stuff" is entered into textfields and passed to a database. Or are you just concerned there are no "http://"s in there?

[degsy]

You can do a simple InStr check

If InStr(str,"http") Then
Response.Write "Error: URL found"
Else
Response.Write "OK"
End If



Or you could use a regular expression

Function isURL(str)
isValid = True
set regEx = New RegExp

regEx.IgnoreCase = False

regEx.Pattern = "(\bhttp://[^ ]+\b)"
isValid = regEx.Test(str)

isURL = isValid
End Function

str = "Joe http://bloggs.com Bloggs"
Response.Write str & "<br>"

If isURL(str) Then
Response.Write "Error: URL found"
Else
Response.Write "OK"
End If