reusable-promise.js

class ReusablePromise {
  constructor() {
    this.executor = this._executor.bind(this);
    this.resolve =
    this.reject =
    this.root =
    this.args =
    this.method = null;
  }
  setup(root, method, ...args) {
    this.root = root;
    this.args = args;
    this.method = method;
    return this;
  }
  then(resolve, reject) {
    this.resolve = resolve;
    this.reject = reject;
    if (this.args) this.method.call(this.root, ...this.args, this.executor);
    else this.method.call(this.root, this.executor);
  }
  // for node style (error, result) callback style async functions
  _executor(err, result) {
    const { resolve, reject } = this;
    this.resolve =
    this.reject =
    this.args = null;
    if (err) reject(err);
    else resolve(result);
  }
}