You can use async/await to implement a Mutex in ES6! It's crazy.

https://gist.github.com/artursapek/70437f6cdb562b7b62e910fd3...

Usage:

    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();

I love it. We use it in our production codebase at Codecademy.