Thank you for your response and for posting in our forum.

I have resolved the issue thanks.

I am checking about the progress of this issue.
Please let me know if you need any further assistance on this.

Hello,

I am glad that this function is working for you. Please take in consideration that if the templated Item is modified and other elements are added, the function should be modified in order to select the actual element that the TextBox is rendered as.

You could even consider using a simplified approach as:

function textboxTextChanged(sender, eventArgs) {

             if (parseInt(sender.parentNode.parentNode.firstChild.children[0].value) < parseInt(sender.value)) {
                sender.value = "";            
            }        
}

Some checks in the function for the first TextBoxValue are also in order, depending on your application specifications, like:
firstTextBoxValue = parseInt(sender.parentNode._object.get_row().get_cellByColumnKey("TemplateField_0").get_element().getElementsByTagName("input")[0].value);

          if ((firstTextBoxValue == (undefined)) || isNaN(firstTextBoxValue) || (firstTextBoxValue < parseInt(sender.value))) {
               sender.value = "";           
         }        
}

I am really glad that you manage to resolve this issue.
Please do not hesitate to contact us if you are still experiencing any issues with this matter.

You know, it might be the difference in the version of the control, between 13.1 and 12.2, but the line you suggested, blew up every time.

However the line below works fine...

  if (sender.parentNode.parentElement._object.get_cellByColumnKey("TemplateField_0").get_element().getElementsByTagName("input")[0].value < sender.value) {

Did you actually run your sample and put entry in the textboxes?