cfgridcolumn validation

Hello experts.
I need help to validate editable cfgridcolumns.
I found a tutorial on this page:http://ajaxian.com/archives/coldfusion-8-grid-magic but i still have problems.
In this example the script is checking if it is a number.I also need to know how it works if i need to check for required fields,maxlength...
Any help?

My cfgrid:
 <cfgrid name="Kategoriegrid" format="html" pagesize="30" insert = "Yes"   sort="yes" width="100%"
    rowheaderbold="yes" colHeaderBold = "Yes"    pictureBar="yes" hspace="0" vspace="0"  bind="cfc:cfc.kategories.getKategories({cfgridpage},{cfgridpagesize},{cfgridsortcolumn},{cfgridsortdirection},{filtercolumn},{filter})" selectmode="edit" onchange= "cfc:cfc.kategories.updateKategories({cfGridAction},{cfgridrow},{cfgridchanged})">
      <cfgridcolumn name="TABLE_ID" header="Table_id"  select="no" display="false"/>
      <cfgridcolumn name="KAT_ID" header="Kat ID" width="30" numberformat="9" <!--- select="no" ---> display="false"/>
      <cfgridcolumn name="KAT_TEXT" header="Text" />
      <cfgridcolumn name="mobiles_sub_id" header="Mobile" select="no"/>
      <cfgridcolumn name="LangID" header="LangID"  select="no"/>
      
   </cfgrid>
<cfset AjaxOnLoad("init")>

my js:
<script language="JavaScript" type="text/javascript">
dataValidator = function(editEvent){
	if (editEvent.field == "Kat_ID"){

         if (isNaN(editEvent.value)){
            alert("Please enter a numeric value in this field.");
            editEvent.cancel = true;
         }
      }
   }
   addValidator = function(){
      mygrid = ColdFusion.Grid.getGridObject('Kategoriegrid');

      mygrid.on('validateedit',dataValidator);
   }
   init = function(){
      addValidator();
   }
</script>

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