Input text value must be start with W,T or Z other character will not Work on keyboard as a first character
<p>Requirement is basically enter a text which Start with 'W','T' or 'Z' and then after we can insert any character or number. I have to use this on Keypress event if we press any key (Except W,T or Z) while entering text in field. The pressed key should not be visible on textbox.</p>

<p>For Example I am using following Script for mobile number validation :</p>

<p>$("[id$=InputTxt]").live('keypress', function(e) {
        return (e.which !=8 &amp;&amp; e.which !=0 &amp;&amp; (e.which &lt; 48 || e.which > 57)) ? false : true;
    }); </p>