JS Regex to match everything inside braces (including nested braces): “{ I want this {and this} and this in one string }”

Question

Meaning that I simply want to strip the enclosing braces. I can match \"{ this kind of stuff }\" with:

\"{stuff}\".match(/{([^}]*)}/)[1]

Am

Answer 1

Regexes are not made for that, and only a few dialects (PCRE and .NET Regex) can cope with recursive structures - JS regex cannot.

So yes, you're asking for too much. Use a JSON parser instead.

Answer 2

I agree with Lucero that Regexes are not made for that, but to answer your question:

The problem is that you match everything except }. But since the inside data you want to match contains itself a }, the content of the outer braces is not matched.

{
    var foo = {
        bar: 1
==> };

    var foo2 = {
        bar: 2    
==> };
}

You can use this regex:

{([\S\s]*)}

To explain:

{                   match opening {
    (               group
        [\S\s]      match everything, workaround for the missing s option in JS
              *     greedy, makes it match as much as possible
    )               end group
}                   match closing }

Answer 3

Try this (I based my code on this answer). It also knows to ignore brackets in strings and comments (single-line and multi-line) - as noted in the comment section of that answer:

var block = /* code block */
    startIndex = /* index of first bracket */,
    currPos = startIndex,
    openBrackets = 0,
    stillSearching = true,
    waitForChar = false;

while (stillSearching && currPos <= block.length) {
  var currChar = block.charAt(currPos);

  if (!waitForChar) {
    switch (currChar) {
      case '{':
        openBrackets++; 
        break;
      case '}':
        openBrackets--;
        break;
      case '"':
      case "'":
        waitForChar = currChar;
        break;
      case '/':
        var nextChar = block.charAt(currPos + 1);
        if (nextChar === '/') {
          waitForChar = '\n';
        } else if (nextChar === '*') {
          waitForChar = '*/';
        }
    }
  } else {
    if (currChar === waitForChar) {
      if (waitForChar === '"' || waitForChar === "'") {
        block.charAt(currPos - 1) !== '\\' && (waitForChar = false);
      } else {
        waitForChar = false;
      }
    } else if (currChar === '*') {
      block.charAt(currPos + 1) === '/' && (waitForChar = false);
    }
  }

  currPos++ 
  if (openBrackets === 0) { stillSearching = false; } 
}

console.log(block.substring(startIndex , currPos)); // contents of the outermost brackets incl. everything inside