It’s almost xMass and typically, each year, I like to get over to Adelaide, South Australia to catch up with family and friends during that period of enforced annual leave. Normally I’d fly. This year however I’m very keen to attempt the drive, having finally bought myself my first car.

When I was about 14 years old my father asked me what kind of car I thought I’d get when I grew up. My response was that I didn’t think I really wanted a car, so much as I wanted a robot to carry me around at high speed, and…

The map function is something offered by all Iterable objects (Arrays, Sets, Lists, etc) and allows you to iterate through the items, apply a transformation to the item, and returns a corresponding collection of the transformed items.

export const VERBS = ['start', 'stop']
export const ACTIONS = VERBS.map(verb => import(`acts/${verb}`))

That’s handy for lots of things, but the above isn’t terribly useful. To get to a function you have to do something like:

import { VERBS, ACTIONS } from 'acts'export default function action(verb) {
  const i = VERBS.indexOf(verb)
  return ACTIONS[I]
}

What’s more useful is if you took the…

Symptom: I am calling a function, getCommonData, loaded from a module called feedScanner. Calling getCommonData() ought to return actual data. It does in unit tests, but, in practice, it’s coming back in its initialised state.

// This fails as it thinks the scanner has not started.const commonData = getCommonData();
console.debug('commonData', commonData);

Investigation: It looks like my hunch was right, there are two feedScanner modules! WTF.

*** Hey I’m a feedscanner ***
*** Hey I’m a feedscanner ***

Javascript imports are cached so why am I seeing two ditinct feedScanner modules?

Investigation: It must be something to do with thewebpack…

Update 2019–12–11: Apple has released Catalina 10.15.2 and iOS 13.3 which, between them, restores the ability for the iOS Remote app to control your Mac based Music library. The instructions below about enabling Home Sharing for Media Sharing still apply.

Update: This works to a point, in that you can actually see your music library in the Remote app, but you can’t actually play anything. This must be a bug. Come on Apple! You’ve really dropped the ball here.

I upgraded my Mac to Catalina (aka macOS 10.15) and amongst the many little changes, iTunes was finally pulled apart and…

This article assumes you are already reasonably familiar with React.

What are hooks?

Hooks are JavaScript functions that let you interact with React components’ state and lifecycle features from plain function components, rather than having to write a class, or wrap components in higher-order components.

Hooks were introduced in React 16.8 and are now a stable feature. Hooks also work in modern versions of React Native.

React provides a number of built-in hooks, and gives you a simple set of rules for writing your own hooks.

The useState hook

The useState hook is probably the…

A standard trope of the climate change denier is that “they”, some unnamed shadowy cabal, stopped referring to “global warming”, and instead rebranded it as “climate change”. While there is some evidence to suggest that this rebadging was attempted by elements of the fossil fuel lobby, the fact is that global warming is not the same thing as climate change; global warming is a driver of climate change.

Climate Change 101

It’s been understood for over a hundred years now that Earth’s atmosphere traps heat by what’s known as “The Greenhouse Effect”. While the physics are not exactly the same as in an…

A while ago I wrote a small utility called amqp-delegate that uses the standard amqplib library to allow the easy creation and invocation of remote workers via an aqmp message bus such as Rabbit MQ.

I wrote an article about this called ‘Delegating Work using NodeJS and AMQP’.

I was at the beach when I wrote it and was feeling pretty lazy. In order to get a nice green 100% coverage badge on my repo I cheated and used /* istanbul ignore next */ to completely ignore my work delegator’s invoke function.

In my tests I added a little TODO…

A slug is a human-readable, unique identifier, used to identify a resource instead of a less human-readable identifier like an id. You use a slug when you want to refer to an item while preserving the ability to see, at a glance, what the item is.

Typically slugs are used when making search-engine optimised urls, so for example the url of this post is https://medium.com/@davesag/whats-a-slug-f7e74b6c23e0. There are actually two slugs in that url, my username, @davesag and the slug for this specific post, whats-a-slug-f7e74b6c23e0. Of that the whats-a-slug part comes from the title, and, for reasons only known to the…