I was reviewing some TypeScript code this afternoon that had a type assertion (as) (also commonly called a ‘cast’) in there that could have been avoided by using a Type Guard. Type Guards are one of my favourite features of TypeScript. That makes me sound like a real nerd. But hey, I might convince you … Read more
You know the drill: leave the office for the day on Wednesday, everything works. Open the laptop Thursday morning, errors everywhere. No? It can’t just be me… surely. Well, today’s issue was when I ran my Jest tests, all of a sudden I started to see this: And this kinda tells you what is wrong. … Read more
In a bid to save you time, I’m going to give you the conclusion I came to after spending several hours both at work, and after work, researching this issue. Do not export enum … from .d.ts files. Enums are runtime values and putting them inside .d.ts files means they will very likely be ignored … Read more
Of all the hooks available in React, useReducer is easily my favourite. It’s nice to be able to solve simple problems with useState, but in component’s with even a smaller amount of complexity than can be solved with a boolean state value, I tend to favour useReducer. Let’s dig in, see some examples, and find … Read more
In this post I will show you a way to create a unit tested React component that allows you to pass either a plain string, or one or more <p>text goes here</p> tags, and then render out only the first X words. When the word limit is hit, a ‘Show More’ button will display, and … Read more
Today’s error is likely going to make you want to kick yourself. I certainly felt like quite a wally after realising my mistake. But I do like to blog these as I hope that by doing so, I shame myself into remembering the solution in the future. OK, the error message: It doesn’t massively impact … Read more
If you’re using TypeScript with Express, you may well hit on TS2339: Property ‘whatever’ does not exist on type ‘RequestQuery’. It’s actually pretty easy to solve. Perhaps more frustrating than anything, as you may well have lots of examples of this problem, especially if migrating an older project from JavaScript, or less restrictive TypeScript, to … Read more
Jest is an amazing testing tool, but sometimes it throws up situations that confuse the hell out of me. Even worse is when I get confused by a problem / error message that I am 100% sure I have seen before, and solved, but it was on a different project and I can’t remember how … Read more
I got really lucky with the fix for this one, as it had me scratching my head for a good while. The gist of this is that I had two classes – a base class, and a sub class. I wanted to call a method with the same name on the sub class as exists … Read more
You may well have come across the warning in React where you are rendering out a list of things, and you forget to give each element a unique key. If you do that, you get the following showing your browser’s console: Warning: Each child in a list should have a unique “key” prop. In this … Read more
