TIL is my collection of short, technical daily learnings. 247 and counting.
Today I used JavaScript to mass-unsubscribe from a website’s email notifications. Here’s the code, followed by what I did and why. document .querySelectorAll('[role="switch"]') .forEach((element) => element.click()); ...
Reflection is an important tool in programming; it lets us examine a language’s structure. Can we reflect in JavaScript? Sort of. Some functions can be reflected with toString(): > const one = () => 1 undefined > one.toString() '() => 1' Very cool! But native functions only return this: > Math.max.toString() 'function max() { [native code] }' You must read the ECMA Script specification to know what the function is required to do. The actual implementation is written in the JavaScript engine, likely in another language like C++, which is why Node can’t show it via toString().
A vital testing skill is focusing a test. When iterating on a failing test, we want that test under microscope. The way I do this in JavaScript is .only: import {describe, expect, test} from 'vitest'; import {sum} from './sum.js'; test('adds 1 + 2 to equal 3', () => { expect(sum(1, 2)).toBe(3); }); describe.only('adding fours', () => { test('adds 4 + 4 to equal 8', () => { expect(sum(4, 4)).toBe(8); }); }); ...
JSDoc has a @deprecated tag that you can use in TypeScript, too. Here’s an example. ...
I’m reading How to Open Source by Richard Schneeman (fantastic) and one of his tips is to show documentation code like this (consider documenting ls): ls <desired-path> Rather than the common: ls /your/path/here ...
When upgrading a dependency for a security issue, we might upgrade and move on: npm install <dependency>@<version> But wait! Was every <dependency> version upgraded, or just the version in package.json? Check with: npm list // or npm ls ...
Today while reading the Rust Documentation, I encountered a fantastic UX touch. The authors provide this image with each code block that intentionally doesn’t compile: ...
Images in Hugo can be a bit tricky. Here’s how I’ve added images on my projects page that are resized, linked, and have alts: the figure shortcode. {{< figure src="/images/yiap.png" alt="Yes, It's a Problem" link="https://github.com/jwworth/yes-its-a-problem" width="600" >}}
Sometimes I want to iterate on an alias. You can unalias an alias like this: unalias aliasname ...
Today I discovered these two Vim flags: vim -w log.txt file vim -s log.txt file The -w flag sends all keystrokes in your session to log.txt. The -s loads Vim and replays all the keystroke back onto that file. ...