Change static value of textbox attributes

 Hi
This works for the page start but once they are on the page and they put text in the box, i need it to blank it out agian for any text they put in there because it will always change.    The Enter SSN part needs to be all text numbers and letters.
txtSearch.Attributes("Onfocus") = "if(this.value == 'Enter SSN'){this.value = ''}"
 
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