Разделить строку JavaScript ТОЛЬКО внешними фигурными скобками

const str = 'hello {world} this is some text. {split me {but not me} thanks} heaps!';

const result = [];
let current = '';
let stack = 0;

for (let i = 0; i < str.length; i++) {
  if (str[i] === '{') {
    if (!stack) {
      result.push(current);
      current = ''
    }
    stack++;
  }

  current += str[i];

  if (str[i] === '}') {
    stack--;
    if (!stack) {
      result.push(current);
      current = ''
    }
  }
}

if (current.length) {
  result.push(current);
}

console.info(result)

const str = 'hello {world} this is some text. {split me {but not me} thanks} heaps!';
const split = str
  .replace(/\{([^}]+)/g, '|{$1') // Mark the first `{` of a section that does not contain a `}`.
  .replace(/([^{]+)\}/g, '$1}|') // Mark the last `}` of a section that does not contain a `{`.
  .split('|')                    // Split the string on the marks.

console.info(split);