jquery - How to prevent user from entering special characters in text box when length is 0? -

i have following code prevents user entering space when length 0. now, how can prevent user entering special characters(anything other a-z a-z 0-9) when length 0?

$('#divisionname').bind('keypress', function(e) {     if($('#divisionname').val().length == 0){         if (e.which == 32){//space bar             e.preventdefault();         }     } });  

this text box.

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

the letter , digit ranges (inclusive):

• 97 - 122 (a-z)
• 65 - 90 (a-z)
• 48 - 57 (0-9)

this compare e.which against.

if (e.which < 48 ||      (e.which > 57 && e.which < 65) ||      (e.which > 90 && e.which < 97) ||     e.which > 122) {     e.preventdefault(); } 

or, using inverse logic:

var valid = (e.which >= 48 && e.which <= 57) || (e.which >= 65 && e.which <= 90) || (e.which >= 97 && e.which <= 122); if (!valid) {     e.preventdefault(); } 

update

even so, may still wish validate field contents whole using regular expression:

if (/^[a-z0-9]+$/i.test(value)) {     // looks okay } 

or fix field replacing bad stuff:

var stripped = value.replace(/[^a-z0-9]+/i, '');