Block special characters from entering textboxes and textareas

Block special characters from entering textboxes and textareas

Hi
I am new to jquery.
I am trying to block special charcters from entering  textboxes and textareas across my application. I have written the below mentioned function in a seperate .js file:
$(document).ready(
function () {
$( 'input[type="text"],textarea' ).bind( 'change' , function () {
// $('textarea[id$=txtfpconfirmcomments]').change(function (event) {
alert( this .id);
if ( this .value.match(/[^a-zA-Z0-9 ]/g)) {
this .value = this .value.replace(/[^a-zA-Z0-9 ]/g, '' );
}
});
});
I have added references in master page:
<script src="scripts/jquery-1.8.2.js" type="text/javascript"></script>
< script src ="scripts/jquery-1.8.2.min.js" type ="text/javascript"></ script >
< script language ="javascript" src ="Scripts/CommentScript.js" type ="text/javascript"></ script >
This function works fine(special characters are getting removed) for textbox when the page is loaded,but if i perform any other action on the page and try to enter special character again in the textbox, it doesnot work at all. But if i refresh the page it starts working again.For textarea its not working fine probably because because the text area is getting loaded on click. Kindly help me solve my issue.