abortable-promise.js

function AbortablePromise (fn) {
  var abortHandler;

  function onAbort (abortFn) {
    abortHandler = abortFn;
  }

  var promise = new Promise(function (resolve, reject) {
    fn.call(null, resolve, reject, onAbort);
  });

  promise.abort = function (reason) {
    abortHandler && abortHandler.call(null, reason);
  }

  return promise;
}

var req = new AbortablePromise(function (resolve, reject, onAbort) {
  var xhr = $.get('/stuff', {
    success: resolve,
    error: reject
  });

  onAbort(function (reason) {
    xhr.abort();
    reject(new Error(reason));
  });
});

setTimeout(function(){
  req.abort('Time is up!');
}, 1000);

request-wrapper.js

function Request (url) {
  this.xhr = new XMLHttpRequest();
  this.promise = new Promise(function (resolve, reject) {
    this.reject = reject
    this.xhr.onload = resolve
    this.xhr.onerror = reject
    this.xhr.open('GET', url)
    this.xhr.send()
  }.bind(this))
}

Request.prototype.then = function (fn) {
  this.promise.then(fn)
  return this
}

Request.prototype.abort = function (reason) {
  this.xhr.abort()
  this.reject(new Error(reason))
}

new Request().then(function(){ console.log('done') }).abort('fudeu');