regex to get the number from the end of a string

i have a id like stringNumber variable like the one as follows : example12 I need some javascript regex to extract 12 from the string."example" will be constant for all id and just the number will be different.

This regular expression matches numbers at the end of the string.

var matches = str.match(/\d+$/);

It will return an Array with its 0th element the match, if successful. Otherwise, it will return null.

Before accessing the 0 member, ensure the match was made.

if (matches) {
    number = matches[0];
}

jsFiddle.

If you must have it as a Number, you can use a function to convert it, such as parseInt().

number = parseInt(number, 10);

RegEx:

var str = "example12";
parseInt(str.match(/\d+$/)[0], 10);

String manipulation:

var str = "example12",
    prefix = "example";
parseInt(str.substring(prefix.length), 10);