mutex.js

// Originally taken from https://github.com/mgtitimoli/await-mutex

class Mutex {
  constructor() {
    this._locking = Promise.resolve();
    this._locked = false;
  }

  isLocked() {
    return this._locked;
  }

  lock() {
    this._locked = true;
    let unlockNext;
    let willLock = new Promise(resolve => unlockNext = resolve);
    willLock.then(() => this._locked = false);
    let willUnlock = this._locking.then(() => unlockNext);
    this._locking = this._locking.then(() => willLock);
    return willUnlock;
  }
}

export default Mutex;

usage.js

import Mutex from 'lib/mutex';

class MyObject {
  constructor() {
    this.m = new Mutex();
  }

  async someNetworkCall() {
    let unlock = await this.m.lock();

    doSomethingAsynchronous().then((result) => {
    // handle result
      unlock();
    }).catch((err) => {
    // handle error
      unlock();
    });
  }
}

let mo = new MyObject();
mo.someNetworkCall();
// The next call will wait until the first call is finished
mo.someNetworkCall();