Захват пар ключ/значение объектной строки (аналогично JSON) с использованием регулярного выражения

const regexKeyValue = /(?<key>\w*)\s*:\s*(?<value>(?<quote>["'])(?:\\.|.)*?\k<quote>|(?<number>[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?)|(?<constant>true|false|null))/g;

document.getElementById('search').addEventListener('click', function () {
  const input = document.getElementById('input').value;

  let match,
      i = 1,
      output = [];

  while ((match = regexKeyValue.exec(input)) !== null) {
    console.info(`Match n°${i} : ` + match[0]);
    console.info('match.groups =', match.groups);

    // If the value is starting with quotes, then unquoted it and
    // also replace all the escape sequences (ex: "\\n" should become "\n").
    let value = match.groups.value;
    // If it's double quotes, let's use JSON.parse() as it will handle everything.
    if (value.match(/^"/)) {
      value = JSON.parse(value);
    }
    // If it's simple quotes, we can't use JSON.parse() so we have to convert
    // it to a double-quoted string before.
    else if (value.match(/^'/)) {
      value = value
        // 1) Remove the simple quotes around.
        .replace(/^'|'$/g, '')
        // 2) Replace all \' by '.
        // We have to search for all backslashes to handle also an escaped backslash.
        .replace(/\\(.)/g, function (fullMatch, afterBackslash) {
          if (afterBackslash === "'") {
            return "'";
          } else {
            return fullMatch;
          }
        })
        // 3) Escape all double quotes (" becomes \").
        .replace(/"/g, '\\"');
      // 4) Now use JSON.parse();
      value = JSON.parse(`"${value}"`);
    }
    
    // If it's a number or a constant, then convert the string to this real JS value.
    if (typeof match.groups.number !== 'undefined' ||
        typeof match.groups.constant !== 'undefined') {
      value = JSON.parse(match.groups.value);
    }

    console.info('value =', value);
    
    output.push(
      `Match n°${i++} :\n` +
      `  Key   : ${match.groups.key}\n` +
      `  Value : ${value}\n`
    );
  }

  document.getElementById('output').innerText = output.join("\n");
  document.getElementById('label').classList.remove('hidden');
});

textarea {
  box-sizing: border-box;
  width: 100%;
}

pre {
  overflow-y: scroll;
}

.hidden {
  display: none;
}

<textarea id = "input" rows = "10">{
  float: 'null',
  another: "foo",
  age: 45,
  type: '"simple" \' quote',
  comment: "Hello,\nA backslash \\, a tab \t and a \"dummy\" word.\nOk?",
  important: true,
  weight: 69.7,
  negative: -2.5
}</textarea>

<button id = "search">Search for key-value pairs</button>

<p id = "label" class = "hidden">Matches:</p>
<pre><code id = "output"></code></pre>

const md=`Some text and now the image: 
![Alt Text]https://<fullurl>.jpg "This is hover text"){prop1: 'foo', prop2: 'bar', float: true} 
and some more text.

A new paragraph any yet nother picture
![Alt Text2]https://<fullerURL>.jpg "This is another hover text"){prop1: 'fool', prop2: 'bart', float: false} and this is the end.`;

function unsafeParse(s){
 return s.match(/\{[^}]+\}/g).map(t=>eval(`(${t})`));
}

// ouputs an array of all image property objects:
console.info(unsafeParse(md));