I want to check if a string ends with ab followed by an integer.

Given any string s, how can I first check if it ends with ab1 or ab2 or ab3, and if so, return ab1 or ab2 or ab3.

For example, for string sdfsadfsab2, I want to return ab2.
For string asdfase I want to return empty string.

Is there any regular expression in javascript or jquery can do this? thanks.

I want to check if a string ends with ab followed by an integer.

Given any string s, how can I first check if it ends with ab1 or ab2 or ab3, and if so, return ab1 or ab2 or ab3.

For example, for string sdfsadfsab2, I want to return ab2.
For string asdfase I want to return empty string.

Is there any regular expression in javascript or jquery can do this? thanks.

• javascript
• jquery

• What have you tried? Regular expressions are a language feature and therefore have nothing to do with jQuery. – Felix Kling Commented Feb 14, 2013 at 20:28
• 1 does 'an integer' include more than one digit? That is, should 'sdgab345' return 'ab345'? – PinnyM Commented Feb 14, 2013 at 20:30

4 Answers 4

The regex you're after could well be:

/ab[0-9]$/

If you want a tester function, that function could look something like this:

function testABInt(string)
{
    var match = string.match(/ab[0-9]$/);
    return match ? match[0] : '';
}

This only matches the end of a string if ab are lower-case chars, and if there is only one int at the end, to match case-insensitive, add the i flag, and/or add a + to match all trailing digits:

/ab[0-9]+$/i

One way using replace:

str.replace(/.*(ab\d+)$/, "$1");

Another way using match:

(str.match(/ab\d+$/) || [""]).pop();

var regex = /([a-zA-Z]{2}[0-9])$/;
var str = "sdfsadfsab2";
console.log(str.match(regex)[0]); //outputs "ab2"

Explanation of regex:

• [a-zA-Z] - a collection of the letters from a-z in lower and upper case
• {2} - meaning "repeated exactly 2 times"
• [0-9] - a collection of the digits from 0 to 9
• $ - meaning "end of the string"

Use $ to match the end of the string:

'foo2'.match(/[a-z]{2}\d$/);