The utf9k logo which is a cartoon robot utf9k


How can I listen for user changes to their colour scheme (ie dark mode)?

While you could provide a button, some parts of a site can look quite nice if they automatically transition between light and dark mode.

You can listen for these changes like so:

window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', e => {
  const updatedScheme = e.matches ? "dark" : "light"
  if (updatedScheme === "dark") {
    // change something to dark mode
  } else {
    // change something to light mode

This can be useful for normal styles but also changes third party assets such as styles on a map.

How can I determine if my code is inside of an iFrame?

I suppose they aren’t used too much anymore but I’ve started using them as a preview window for my projects page.

It can be handy to act different depending on an iFrame, such as scaling the view port.

You can’t do something like this:

iframe > canvas {
  width: 500px;

canvas {
  width: 100%;

but you can use Javascript inside an iFrame and make the changes within the frame itself, rather than from the outside:

function insideIframe() {
  try {
    return window.self !==
  } catch (e) {
    return true

if (insideIframe()) {
  // perhaps change the size of something or just act differently

Where can I determine my NODE_MODULE_VERSION

This error is usually pretty cryptic and I often forget how to debug it so let’s look at a sample error:

Error: The module '/Users/marcus/Code/octowise/node_modules/better-sqlite3/build/Release/better_sqlite3.node'
was compiled against a different Node.js version using
NODE_MODULE_VERSION 83. This version of Node.js requires

I often remember that I need to possibly use a different version of nodejs but I never remember how to tell which one.

The official NodeJS site has a table with version numbers and their corresponding NODE_MODULE_VERSION available here.

In the case of this error, I think I probably want to downgrade to Node.js 14.x? It’s all very confusing.

Did you like this post? Click here to let me know anonymously or see some proof of anonymity first.