A Pattern For Cancelling Fetch API Requests
There is a fairly reproducible bug in outlook.office.com that occurs when you quickly switch back and forth between Calendar and Mail while everything is still loading in:
Outlook thinks you are in the Calendar when actually it is the Mail section that loaded in last. The navigation basically stops working at that point.
I’m picking on Outlook because it is a major web application that presumably has a large quality assurance team behind it. But once you start to look for these out-of-order execution bugs, you can see them pop up in just about every JavaScript application.
Using The Null Object Pattern With 3rd Party Types
Feel free to skip ahead if you are already familiar with the Null Object Pattern. What follows is a quick introduction to the pattern.
Imagine you want to format a money object before displaying it to the user, but the problem is that the object might be null. Any coder knows how to handle that:
const formatMoney = (money) => {
if (money === null) {
return '[price unavailable]';
}
return money.format();
};
console.log('it costs ' + formatMoney(getPrice()));
Nothing wrong with that code, right?
But what if I told you we could simplify the same code to this:
console.log('it costs ' + getPrice().format());
How would that even work?? How does .format() not throw TypeError: Cannot read property 'format' of null when getPrice() returns null?
In one sense it is impossible to avoid throwing an error. However, the funny thing about impossible challenges is how often they become possible after examining one’s assumptions.
Things I Wish Someone Told Me About ASP.NET Core WebSockets
There are lots of WebSocket tutorials out there for ASP.NET Core MVC. They all seem great if you are trying to make a demo chat app. Unfortunately, they don’t cover most of the things that are going to trip you up when you go to write a production-ready app. What follows is an assorted list of the things I have learned so far.
How To Not Suck With PowerPoint
Everyone hates on PowerPoint. There’s much to hate about PowerPoint. At the end of the day though, it’s just a tool.
I want to show you how to wield PowerPoint for good. However in order to do that, first we need to understand why PowerPoint is bad.
Perhaps it’ll be easier to show you what I mean:
You probably recognize this slide. This is what every PowerPoint slide ever presented looks like.
CSS Specificity Explained In 300 Words
If you’ve done much CSS, you’ve probably run into this issue:
/* a rule defined in some common/library code */
.some-component .some-element {
color: red;
}
/* ...somewhere else in a file you're working on... */
.some-element {
color: blue; /* doesn't work. why? */
}
You added some CSS to make the element blue, but for some reason a CSS rule defined earlier in some library is overriding your style. What gives?