SO Answer: javascript regex to disallow all special characters

See: http://stackoverflow.com/questions/15243387/javascript-regex-to-disallow-all-special-characters

HTML

<input type="text" id="value" />

JavaScript

$('#value').bind('keypress', function(e) {
			if($('#value').val().length == 0){
                if (e.which == 32){//space bar
            	    e.preventDefault();
                }
                var valid = (e.which >= 48 && e.which <= 57) || (e.which >= 65 && e.which <= 90) || (e.which >= 97 && e.which <= 122);
if (!valid) {
    e.preventDefault();
}
			}
        });