How to NOT allow users to enter HTML in text box?

I just found the HTMLCODEFORMAT() function, which seems to do the trick upon inserting into the database.  But, if there is a better way than this, please let me know.  I want to make sure that people will not be able to change the look of the page in any way.

That is really the best way.

Also you can look into cfqueryparam tag  for protection from other items like sql injection and other evils.

There is also a cf custom tag you can include to strip any html

I put it in my application.cfm and it strips any html from url and form variable being passed.

<!---
      
      Template:                        inputfilter.cfm
      Author:                        Peter Muzila
      
      Source Control:            $Header: $
      
      Description:
      
            The cf_inputFilter tag removes characters or tags from all fields coming from the
            specified scopes (form,cookie, or url). This tag can be placed in the Application.cfm
            file to filter out any input coming thru these scopes to any of the templates belonging
            to the application.cfm file.
            
            This tag can be executed only with CF 4.5 or higher
      
      Usage:
      
            <cf_inputFilter
                  scopes = "[FORM][,COOKIE][,URL]"
                  chars = "list_of_chars"
                  tags = "ALL|list_of_tags"
            >

      Attributes:

            scopes (string list, required) - comma-delimited list of input scopes to be filtered
            chars (string, optional) - string containing set of characters to be filtered out from the
                  input scope
            tags (string list, optional) - comma-delimited list of tag names to be filtered out from the
                  input scope
                  
            
--->

<!--- attributes validation --->
<cfparam name="attributes.scopes">
<cfparam name="attributes.chars" default="">
<cfparam name="attributes.tags" default="">


<cfscript>

      // prepare reg expression for the tag search
      reTags = "" ;
      if ( attributes.tags eq "ALL" )
            // re for any tag - "<*>"
            reTags = "<[^>]*>" ;
      else if ( attributes.tags neq "" )
            // re for any of the listed tags - "<tag1|tag2|...|tagN>"
            reTags = "</?(#ListChangeDelims(attributes.tags,  '|', ',' )#)[^>]*>" ;
            
      // get comma-delimited list of chars from char set
      charList = '' ;
      if ( attributes.chars neq "" ) {
            charList = attributes.chars ;
      
            for ( i=Len(attributes.chars)-1; i gte 1; i=i-1 )
                  charList = Insert( ",", charList, i ) ;
      }

</cfscript>


<cfloop list="#attributes.scopes#" index="scopeName">
      <cfif not findnocase("multipart/form-data",cgi.CONTENT_TYPE)>
            <cfscript>
      
                  // get the handle for the scope (form, cookie, url)
                  s = Evaluate( scopeName ) ;
      
                  // scroll thru fields in the scope and handle only simple values
                  for ( field in s )
                        if ( IsSimpleValue( s[field] ) ) {
                              
                              // replace tags
                              if ( reTags neq '' )                        
                                    s[field] = REReplace( s[field], reTags, "", "ALL" ) ;
                        
                              // replace chars
                              if ( charList neq '' )                                                      
                                    s[field] = ReplaceList( s[field], charList, "" ) ;
      
                        }
      
            </cfscript>
      </cfif>

</cfloop>


Regards

Gary

I decided against the HTMLCODEFORMAT() tag because it inserts <pre></pre> into the text field after it is submitted to the database.  It also changes the way the text looks when displayed.

I tried using the custom tag (above) but it was not working.  I put this in the application file:   <cf_inputFilter
scopes = "FORM,COOKIE,URL"
tags = "ALL">.  Did I do something wrong?

The only way I got it to work was a combination of using the custom tag & this:
<cfscript>
attributes.fieldname = REReplace(attributes.fieldname , "<[^>]*>","","ALL");
</cfscript>

When used separately (without both), the HTML tags were not deleted.  But when used together, everything within <> is removed.  Why did I have to use both the script & the custom tag to do this?

I am not sure why you had to use both.  The script should have worked fine.

Actually, I just deleted the cf tag from the application file & just using the script, which is removing anything between HTML tags, which is what I want.  So what do I gain by using the custom tag?

For your need, you do not gain anything.  It was just an alternate solution.

I am glad that the script I posted is working for you.