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domenic /
Last active Apr 6, 2021
Auto-deploying built products to gh-pages with Travis

Auto-deploying built products to gh-pages with GitHub Actions

This is a set up for projects which want to check in only their source files, but have their gh-pages branch automatically updated with some compiled output every time they push.

A file below this one contains the steps for doing this with Travis CI. However, these days I recommend GitHub Actions, for the following reasons:

  • It is much easier and requires less steps, because you are already authenticated with GitHub, so you don't need to share secret keys across services like you do when coordinate Travis CI and GitHub.
  • It is free, with no quotas.
  • Anecdotally, builds are much faster with GitHub Actions than with Travis CI, especially in terms of time spent waiting for a builder.
domenic /
Created Feb 10, 2017
Redirecting GitHub pages after a repository move

Redirecting GitHub Pages after a repository move

The problem

You have a repository, call it alice/repo. You would like to transfer it to the user bob, so it will become bob/repo.

However, you make heavy use of the GitHub Pages feature, so that people are often accessing GitHub will helpfully redirect all of your repository stuff hosted on after the move, but will not redirect the GitHub Pages hosted on

The solution

domenic /
Last active Apr 2, 2021
You're Missing the Point of Promises

This article has been given a more permanent home on my blog. Also, since it was first written, the development of the Promises/A+ specification has made the original emphasis on Promises/A seem somewhat outdated.

You're Missing the Point of Promises

Promises are a software abstraction that makes working with asynchronous operations much more pleasant. In the most basic definition, your code will move from continuation-passing style:

getTweetsFor("domenic", function (err, results) {
    // the rest of your code goes here.
domenic / upload.js
Created Mar 20, 2012
File upload using XHR PUT
View upload.js
(function () {
var $dropTarget = $("#drop-target");
var slice =;
drop: function (event) {
return false;
domenic / angularpromise.js
Created Jan 21, 2016
How to subclass a promise
View angularpromise.js
// ES6
class AngularPromise extends Promise {
constructor(executor) {
super((resolve, reject) => {
// before
return executor(resolve, reject);
// after
domenic / event-emitter.js
Last active Mar 8, 2021
Revealing constructor pattern event-emitter
View event-emitter.js
// This event emitter emits events, but reserves the right to publish events to
// for its creator. It uses a WeakMap for true encapsulation.
const eesToEventMaps = new WeakMap();
export default class EventEmitter {
constructor(publisher) {
const eventMap = Object.create(null);
eesToEventMaps.set(this, eventMap);
domenic /
Last active Feb 25, 2021
`module.exports =` and ES6 Module Interop in Node.js

module.exports = and ES6 Module Interop in Node.js

The question: how can we use ES6 modules in Node.js, where modules-as-functions is very common? That is, given a future in which V8 supports ES6 modules:

  • How can authors of function-modules convert to ES6 export syntax, without breaking consumers that do require("function-module")()?
  • How can consumers of function-modules use ES6 import syntax, while not demanding that the module author rewrites his code to ES6 export?

@wycats showed me a solution. It involves hooking into the loader API to do some rewriting, and using a distinguished name for the single export.

This is me eating crow for lots of false statements I've made all over Twitter today. Here it goes.

domenic / escape-vm.js
Created Aug 17, 2015
Escaping the vm sandbox
View escape-vm.js
"use strict";
const vm = require("vm");
const sandbox = { anObject: {} };
const whatIsThis = vm.runInNewContext(`
const ForeignObject = anObject.constructor;
const ForeignFunction = ForeignObject.constructor;
const process = ForeignFunction("return process")();
const require = process.mainModule.require;
domenic / 1-service-worker.js
Last active Jan 1, 2021
Service worker stream transferring
View 1-service-worker.js
"use strict";
const worker = new Worker("worker.js");
self.onfetch = e => {
const transform = new TransformStream(); // creates an identity transform
e.respondWith(new Response(transform.readable));
// Give the worker the writable end. An identity transform stream will just shuffle
// bytes written there into transform.readable.
domenic / promise-retryer.js
Last active Dec 23, 2020
Generalized promise retryer
View promise-retryer.js
"use strict";
// `f` is assumed to sporadically fail with `TemporaryNetworkError` instances.
// If one of those happens, we want to retry until it doesn't.
// If `f` fails with something else, then we should re-throw: we don't know how to handle that, and it's a
// sign something went wrong. Since `f` is a good promise-returning function, it only ever fulfills or rejects;
// it has no synchronous behavior (e.g. throwing).
function dontGiveUp(f) {
return f().then(
undefined, // pass through success