Javascript Regex To Match Only Up To 11 Digits, One Comma, And 2 Digits After It

I have a textbox where I want only allowed up to 11 digits, an optional comma, and two more digits after it. Anything else should not be rendered when the key is pressed into the t

Solution 1:

You should test your complete string, not only the current letter.

$('#txt').keypress(function (e) {
    var key = String.fromCharCode(e.which);
    var pattern=/^[0-9]{1,11}(,[0-9]{0,2})?$/;

    // test thisvar txt = $(this).val() + key;

    if (!pattern.test(txt)) {
        e.preventDefault();
    }
});

​

jsfiddle example

Solution 2:

This regex will match any string containing 1 up to 11 digits optionally followed by a , and exactly 2 more digits: ^[0-9]{1,11}(,[0-9]{2})?$

Explanation:

^             # Match the start of the string
[0-9]{1,11}   # Followed by a maximum of 11 digits
(,[0-9]{2})?  # Optionally followed by a comma and 2 more digits $ # Followed by the end of the string

See it in action here.