Function map

packages/engine.io/lib/parser-v3/index.ts:255–267

* Async array map using after

(ary, each, done)

 */

function map(ary, each, done) {
  const results = new Array(ary.length);
  let count = 0;

  for (let i = 0; i < ary.length; i++) {
    each(ary[i], (error, msg) => {
      results[i] = msg;
      if (++count === ary.length) {
        done(null, results);
      }
    });
  }
}

/*
 * Decodes data when a payload is maybe expected. Possible binary contents are