Function join

src/CollectionImpl.js:215–226

(separator)

  },

  join(separator) {
    assertNotInfinite(this.size);
    separator = separator !== undefined ? '' + separator : ',';
    let joined = '';
    let isFirst = true;
    this.__iterate((v) => {
      // eslint-disable-next-line @typescript-eslint/no-unused-expressions -- TODO enable eslint here
      isFirst ? (isFirst = false) : (joined += separator);
      joined += v !== null && v !== undefined ? v.toString() : '';
    });
    return joined;
  },

  keys() {
    return this.__iterator(ITERATE_KEYS);