Wait some async scripts

Waiter.js

/**
 * Wait some async stuff
 *
 * usage
   let waitStuff = new Waiter('tns', 'function', () => { // callback }).check();
 */
class Waiter {
  constructor(what, type, callback, timeout = 100, attempts = 50, from = window) {
    this.what = what;
    this.type = type;
    this.callback = callback;
    this.timeout = timeout;
    this.attempts = attempts;
    this.count = 0;
    this.from = from;
  }

  check() {
    if (this.count >= this.attempts) {
      return;
    }

    this.count++;

    if (typeof this.from[this.what] === this.type) {
      this.callback();
    } else {
      setTimeout(() => {
        this.check();
      }, 100);
    }
  }
}