Oak, the successor of Koa (which is the spiritual successor of Express in Node.js), is the most popular choice when it comes to building web applications with Deno. However, when saying web applications with Deno, it's often not for anything visible in the browser (excluding server-side rendering of a frontend application). Instead, Oak, a web…

Handling errors in Express is often an afterthought. However, it should usually start with your Express routes, because if an error happens, your user needs to be notified about it. With the right techniques at hand, error handling in Express becomes pretty straight forward. There are several scenarios why an error might happen. It can be that a…

React's memo API can be used to optimize the rendering behavior of your React function components . We will go through an example component to illustrate the problem first, and then solve it with React's memo API . Keep in mind that most of the performance optimizations in React are premature. React is fast by default, so every performance…

Environment variables are great for hiding sensitive information about your Deno application. This can be API keys, passwords, or other data which shouldn't be visible to others. That's why there exists the .env file, which you would have to create, to hide sensitive information. We will create this file and pass some sensitive information to it…

Deno is a new runtime for JavaScript and TypeScript. If this doesn't tell you much and you don't know what to expect, then take this statement as secondary introduction: Ryan Dahl, inventor of Node.js, released Deno in 2020 as answer to improve Node.js. However, Deno isn't Node.js, but a complete new runtime for JavaScript, but also TypeScript…

The countBy function is one of the functions why people use Lodash in their JavaScript code base. Here I want to give you a brief example on how to implement countBy in vanilla JavaScript without Lodash by just using JavaScript's reduce method. Let's say we have the following array of objects and we want to count them by property (here color…

The groupBy function is one of the functions why people use Lodash in their JavaScript code base. Here I want to give you a brief example on how to implement groupBy in vanilla JavaScript without Lodash by just using JavaScript's reduce method. Let's say we have the following array of objects and we want to group them by property (here color…

Eventually everyone came across the case that JavaScript's replace function, which is available on a JavaScript string primitive , does only replace one occurrence of the matched term. Here I want to show you briefly how to replace all occurrences in JavaScript with two different ways. The first way uses a regular expression to find all matches…

Functions are first-class citizens in JavaScript. That's why you will early on hear about callback functions in JavaScript, which are a super powerful asset when writing JavaScript code. Here I want to give you a brief introduction to them. Callback functions are usually passed as argument to functions: In this case, our printText function takes…