In this article, we aim to create and publish a library that can be used, without any changes in the code, in both client side and server side applications.

We need to fulfill the following use cases:

In this article, we explain the new JSX Transform, and how to use JSX without React.

The official React blog does not get many updates, so a new post is always attention worthy, but this week’s post, Introducing the New JSX Transform, could be a much bigger deal than it seemingly appears.

In this post, Luna Ruan announces a new JSX Transform, and one of the…

I received an email digest from a popular blogging platform which included after the first few serious and news worthy links some more click-baity content. The article that caught my eye is titled something along the lines of “Questions and Answers to Algorithm Interviews”. In my experience, with few exceptions…

In this article we’ll see how to use environment variables in a React application. Specifically, we’ll look at two kinds of environments variables:

June 2021 update: while some of the content of this article remains accurate (and hopefully useful), it is a bit of a contrived example. It assumes that there is an existing REST api running on Express that needs to be maintained, while also exposing a GraphQL endpoint. In reality, a…

Redis is, according to its own website, “an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker”.

In other words, Redis can be used as a blazing fast cache, and it’s dead simple to use.

Let’s use as an example a simple Express…

Clean code is code that is easy to understand, easy to review and easy to change.

Ternaries, especially as one line functions, are rarely any of these things.

Let’s write a function that returns whether an integer is positive or negative. This can be simply and quickly written as is:

Before getting too deep in the weeds, we need to understand what immutability is. It all has to do with reference and value equality.

Reference equality: we compare references (pointers), and if the two instances are the same, then obj1 === obj2

Value equality: we compare values, and if the…

Working with currencies in JavaScript can be more complicated than it seems.

The first issue we have is that a monetary amount is usually represented using a float, so multiplying and dividing them can be tricky. Just try typing 10 / 3 or 3.33 * 3 in a JavaScript console.

1. Use destructuring to swap variables

let a = 1;
let b = 2;
console.log(a, b); // 1 2
[a, b] = [b, a]; // Magic swap!
console.log(a, b); // 2 1

2. Use the Spread operator to create a function that accepts a variable number of arguments

const add = (...numbers) => { // numbers is an array!
const sum = numbers.reduce((sum, n) => sum + n, 0);

Arnaud Dostes

Previously Paris and Geneva, currently New York. Can also be found at

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