How would I go about splitting a string by two brackets with regex?

Question

I have been working with Discord.js and Node to a quick bot to look up something. I need a way to find all the occurrences that appear between two square brackers and store them in an array of strings. For now I'm using string-split() with some regex, but I am unsure of the regex to use.

I have tried using a few different ones, including /[^\[\[]+(?=\]\])/g and \[\[(.*?)\]\] - I dont mind having the actual brackets in the results, I can remove them manually with string.replace().

I am also working on a fallback with the normal string.split() and other string functions, not relying on regex, but I'm still curious about a possible regex version.

The result with the first regex is totally incorrect. For example, if I try "does [[this]] work [at all]?" the output is "[[]]" and "[at all]", when it really shouldn't take the "at all", but it shouls show the "[[this]]".

With the second regex I get somewhat closer, it gives back "this"(correct) and "[at all]" (again, it shouldn't take the "at all").

I don't mind having the brackets in the output, I can remove them manually myself, but I need to find all occurrences that are specifically between two brackets.

and your second regex just works well https://regex101.com/r/z6qpHJ/1 — apple apple, Apr 27 '19 at 14:15
it should be `"does [[this]] work [at all]?".match(/\[\[(.*?)\]\]/g)`, and this at least work in my browser (you don't even need the g flag) — apple apple, Apr 27 '19 at 14:17
with .match it only matches the first result, with or without the global flag — Rainfall, Apr 27 '19 at 14:32
`"it's [[not]] the case for my browser [[at all]].".match(/\[\[(.*?)\]\]/g)` — apple apple, Apr 27 '19 at 14:45
I should have made it clear, I am using node for this. that does work on my browser too, just not with the node bot — Rainfall, Apr 27 '19 at 15:02
According to [this answer](https://stackoverflow.com/a/50434875/5424988), you might use a positive lookabehind which in Node.js v6 is behind a flag and v9 without a flag `(?<=\[\[)[^\][]+(?=\]\])` See a [demo](https://repl.it/repls/ParallelSleepyButton) — The fourth bird, Apr 28 '19 at 11:15

Todd Chaffee · Answer 1 · 2019-04-27T14:56:52.603

0

Try this regex:

\[\[([^[\]]|(?R))*\]\]

What you are trying to do is called Matching Balanced Constructs. More info at the link.

Upon further testing, unfortunately JS does not support (?R) so this becomes far more difficult. You could use the XRegExp.matchRecursive addon from the XRegExp package.

And your expression \[\[(.*?)\]\] should work. Working example below.

var str = 'does [[this]] work [at all] with another double [[here]]?';

var result = str.match(/\[\[(.*?)\]\]/g);

var newDiv = document.createElement("div"); 
newDiv.innerHTML = result;
document.body.appendChild(newDiv);

edited Apr 27 '19 at 14:56

answered Apr 27 '19 at 14:06

Todd Chaffee

6,754
32
41

with the ?R it just errors on execution, with "Invalid regular expression: Invalid group". removing ?R (so that it works on regex101.com) and testing with `does [[this]] work [please] [[cmon]] bot` it returns "does", "s", "[please]", "n", and "bot". – Rainfall Apr 27 '19 at 14:22
Ah, I just noticed JS doesn't support `(?R)`. I'll update the answer in a few minutes with a JS compatible solution. – Todd Chaffee Apr 27 '19 at 14:26

score 0 · Answer 2 · answered Apr 28 '19 at 14:27

0

Try my solution

var str = "does [[this]] work [at all]?";
var regexp = /\[([a-z0-9\s]+)\]/ig;

var resultArray = str.match(regexp); 
resultArray = resultArray.map((item) => {
  return item.replace(/(\[|\])/g, "");
})

console.log(resultArray);

answered Apr 28 '19 at 14:27

Alonad

1,986
19
17

How would I go about splitting a string by two brackets with regex?

2 Answers2