Sharepoint form-check for spam words and prevent submission

Looking for:

If 'these words' are entered in this text box

Disable the submit button

Otherwise, submit.

This works for empty required fields:

<xsl:if test="@Required='TRUE'">
           <span style="color:#FF0000;font-size:14px;">&#160;*</span>
         </x开发者_如何学编程sl:if>       

But can't seem to make it work to test for unwanted words.

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the above code is for displaying * in red color not for disabling the submit button. in case you need to disable the submit button you have to attach javascript to do the same