user2255785 user2255785 - 1 year ago 57
Javascript Question

Prevent duplicate comma from being typed into Input Text Box

I'm using a textbox to collect numbers only, separated by a comma. No other characters, not even spaces, are allowed. Only 0-9 and a comma.

The following function serves my purpose, but I'd like to now prevent a duplicate comma from being entered.

e.g. 22,444,2,444

e.g. 22,,444,2,444 OR 22,,444,,2,,444

Here is the code I'm using for limiting the field to numbers, and allowing only a comma:

$("#customPrices").keypress(function (e) {

if (e.which != 8 && e.which != 0 && String.fromCharCode(e.which) != ',' && (e.which < 48 || e.which > 57))

//display error message
if($( "#errmsg" ).is(':hidden'))
$( "#errmsg" ).fadeIn();
return false;



I've found something that may be able to work at the following link:
Javascript Help - prevent duplicate characters in textbox

The example there needs to prevent a hyphen, which is charCode 45. A comma is charCode 44....

But I'm not sure of how to implement it into my current code...

Any help would be really loved, thank you!

Answer Source
add the below condition:
1) take the existing value
2) check the last char is (,) and current char also (,) and validate
 var customPrices = $("#customPrices").val();

String.fromCharCode(e.which) == ',' && String.fromCharCode(e.which) == 

String.fromCharCode(e.which) == ',' && customPrices.charAt(customPrices.length-1) == ','