Increment 3rd occurence of digit in string with javascript

Question

I have the following string:

[group][100][250][3][person]

and I need to increment the number 3 . I tried the regex /\\[\\d+\\]/ which matches all 3, but I couldn't get anywhere from here.

Answer 1

You could do it by matching all 3 of your numeric values and just increment the third:

 var regex = /\\[(\\d+)\\]\\[(\\d+)\\]\\[(\\d+)\\]/g var input = "[group][100][250][3][person]"; var result = input.replace(regex, function(match,p1,p2,p3){ return "[" + p1 + "][" + p2 + "][" + (parseInt(p3,10) + 1) + "]" }) console.log(result); 

Answer 2

You can use .replace with a callback function:

 var s = "[group][100][250][3][person]"; var repl = s.replace(/((?:\\[\\d+\\]){2}\\[)(\\d+)\\]/, function($0, $1, $2) { return $1 + (parseInt($2)+1) + ']'; } ); console.log(repl); //=> "[group][100][250][4][person]" 

Answer 3

To capture "your" string, try the below regex:

(?:\[\d+\]){2}\[(\d+)\]

How it works:

• (?:...){2} - a non-capturing group, occuring 2 times.
• \\[\\d+\\] - containing [ , a sequence of digits and ] .
• [ , a capturing group - sequence of digits and ] .

The text you want to capture is in the first capturing proup.