Smallest Asynchronous Flow Control implementation in JavaScript

async-fn.js

  // use like: forEachAsyncSerial(Post.find(), (next, post) => { /* ... */ next(); }, () => { /* done! */ });
  static forEachAsyncSerial(a, each_cb, done_cb) {
    let i = 0;
    const next = () => {
      if (i >= a.length || false === each_cb(next, a[i++])) {
        if ('function' == typeof done_cb) done_cb();
      }
    };
    process.nextTick(next);
  }

  static whileAsyncSerial(test, each_cb, done_cb) {
    const next = () => {
      if (!test() || false === each_cb(next)) {
        if ('function' == typeof done_cb) done_cb();
      }
    };
    process.nextTick(next);
  }
  
  static ifAsync(/* test, true_fn, args..., done_cb */) {
    let args = Array.prototype.slice.call(arguments);
    let test = args.shift();
    let done_cb = args.pop();

    if (test) {
      let true_fn = args.shift();
      args.push(done_cb);
      true_fn.apply(null, args);
    }
    else {
      done_cb();
    }
  }