CODEWITHSUNDEEP
javascriptregex
Jason Kelly
Jason Kelly

Reputation: 2655

Function changes my string to a completly different value

I need your help,

I have the following function below. What is happening, is that when it is executed it changes my native file number (x) to XAI-2012-402518 when all it is supposed to is add a -2 at the end and then increment it every single time after that.

The desired result is: XAI-2012-402517-2 and not XAI-2012-402518

Regularly, without any dashes in the string, it works just fine, but I think the function is confusing the dashes.

Other examples are:

filenumber -> filenumber-2
filenumber2 -> filenumber-3
XAI-2012-402517 -> XAI-2012-402517-2
XAI-2012-402517-2 -> XAI-2012-402517-3
XAI-2012-402517-3 -> XAI-2012-402517-4

ect.

function test2(){ 
    var x = "XAI-2012-402517"

    x = x.replace(/^(.+?)(-\d+)?$/, function(a,b,c) { return c ? b+(c-1) : a+'-2'; } );

    alert(x)
}

Upvotes: 0

Views: 52

Answers (1)

Ilya Kharlamov
Ilya Kharlamov

Reputation: 3932

Your function works exactly right. You have an algorithm "capture a digit that comes after the last dash and increase it by one". In "XAI-2012-402517", the digit that comes after the dash is 402517 and therefore it needs to be incremented.

In order to fix this, you need to put a limitation to the condition. For example you may wish to increase only the last digit after dash if it is less than 100:

    function test2(x){ 
            x = x.replace(/^(.+?)(-\d{0,2})?$/, function(a,b,c) { 
            return c ? b+(c-1) : a+'-2'; } );
            console.log(x)
    }
    test2("XAI-2012-402517") //XAI-2012-402517-2
    test2("XAI-2012-402517-2") //XAI-2012-402517-3

Upvotes: 1

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