Quick Async Promise Hack

gistfile1.js

var orderOfExecution = [];

function mockResolve_ (promise, resolvedVal, rejectedVal) {
  promise.resolvedVal = resolvedVal;
  promise.rejectedVal = rejectedVal;
}

function flush (promise) {
  promise.resolveNext_.call(promise);
};


Promise.prototype.then = function (good, bad) {
  this.chain_ = this.chain_ || [];
  this.chain_.push({resolve: good, reject: bad});
  return this;
}

Promise.prototype.resolveNext_ = function () {
  if (!this.chain_) return;
  var next = this.chain_.shift(), nextVal;
  if (!next) return;

  if (this.resolvedVal) {
    next = next.resolve;
  }
  else {
    next = next.reject;
  }
  
  nextVal = next ? next.call(this, this.resolvedVal) : null;
  nextVal && this.resolveNext_();
}


var p = new Promise(function (resolve, reject) {
  resolve('10 seconds later');
}).
then(function() {
  orderOfExecution.push('thenResolve');
});

mockResolve_(p, 'value');
flush(p);

orderOfExecution.push('postFlush');

if (orderOfExecution[0] === 'thenResolve' && orderOfExecution[1] === 'postFlush') {
  console.log('Synchronous execution!');
}
else {
  console.log('Execution was NOT synchronous');
}