Re-replacing in regex

Question

I am creating a function that replaces the string with a

~(number)~.

Now let's say I have a string that says This is the replacement of ~26~ and ~524~. We still have 2 cadets left. Have2go for the next mission.2

I want to replace all the 2 in a string with ~86~ but when I am doing so the 2 in ~26~ and ~524~ also getting replaced to ~~86~6~ and ```~5~86~4~.

function replaceGameCoordinate() {
  var string = `This is the replacement of ~26~ and ~524~. We still have 2 cadets left. Have2go for the next mission.2`
  var replaceArr = ['2'];
  let patt = new RegExp(`${replaceArr[0]}`, 'gm')
  var newString = string.replace(patt, "~86~");
  console.log(newString);
}
replaceGameCoordinate();

The expected output should be :

This is the replacement of ~26~ and ~524~. We still have ~86~ cadets left. Have~86~go for the next mission.~86~

Your regex is working for all 2 but this is not replacing the 2 in have2go — Vipin Gautam, Nov 01 '20 at 13:09
`/(?<!\d)2(?!\d)/` is what you need. ``new RegExp(String.raw`(?<!\d)${replaceArr[0]}(?!\d)`, 'g')`` — Wiktor Stribiżew, Nov 01 '20 at 13:36
[Here it is](https://stackoverflow.com/a/41807955/3832970). This is a very typical and common issue, no need for another answer. — Wiktor Stribiżew, Nov 01 '20 at 14:05

score 0 · Accepted Answer · answered Nov 01 '20 at 13:13

0

So you need a different regex rule. You don't want to replace 2. You want to replace 2 when it's not next to another number or ~.

In order to do this, you can use lookaheads and lookbehinds (although lookbehinds are not yet supported by regexes in JS, I believe, but at least with lookaheads) :

const input = "This is the replacement of ~26~ and ~524~. We still have 2 cadets left. Have2go for the next mission.2";

const regex = /2(?![\d~])/gm // Means : "2 when it's not followed by a digit \d or a ~"

console.log( input.replace(regex, "~86~" ) )

answered Nov 01 '20 at 13:13

Jeremy Thille

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It will stil match `12` – anubhava Nov 01 '20 at 13:26
Indeed, but not `~12~` or `~123~`, so it fits the bill. Feel free to submit a better answer :) – Jeremy Thille Nov 01 '20 at 13:29
...and OP replied `Your regex is working for all 2 but this is not replacing the 2 in have2go`. So it looks like my proposition still works better :) – Jeremy Thille Nov 01 '20 at 13:34
1

if I have something like 2~24~ then it is also not replacing that 2 . I also want to replace that – Vipin Gautam Nov 01 '20 at 13:45
So, define a precise set of rules. My reply answered the original problem, but now the rules have changed. – Jeremy Thille Nov 01 '20 at 13:55

Re-replacing in regex

1 Answers1