This deals with the general problem of extracting a signed number from a string that also contains hyphens.

Can someone please e up with the regex for the following:

 "item205"             => 205  
 "item-25              => -25  
 "item-name-25"        => -25  

Basically, we want to extract the number to the end of the string, including the sign, while ignoring hyphens elsewhere.

The following works for the first two but returns "-name-25" for the last:

var sampleString = "item-name-25";
sampleString.replace(/^(\d*)[^\-^0-9]*/, "")

Thanks!

This deals with the general problem of extracting a signed number from a string that also contains hyphens.

Can someone please e up with the regex for the following:

 "item205"             => 205  
 "item-25              => -25  
 "item-name-25"        => -25  

Basically, we want to extract the number to the end of the string, including the sign, while ignoring hyphens elsewhere.

The following works for the first two but returns "-name-25" for the last:

var sampleString = "item-name-25";
sampleString.replace(/^(\d*)[^\-^0-9]*/, "")

Thanks!

• javascript
• regex

• 2 Any particular reason this was voted down? Seems perfectly valid... – Randy Hall Commented Dec 7, 2012 at 17:40

2 Answers 2

You can use .match instead:

"item-12-34".match(/-?\d+$/);  // ["-34"]

The regexp says "possible hyphen, then one or more digits, then the end of the string".

Don't use replace. Instead, use match and write the regex for what you actually want (because that's a lot easier):

var regex = /-?\d+$/;
var match = "item-name-25".match(regex);
> ["-25"]
var number = match[0];

One thing about your regex though: in a character class you can only meaningfully use ^ once (right at the beginning) to mark it as a negated character class. It doesn't work for every single element individually. That means that your character class actually corresponds to "any character that is not a -, ^ or a digit.