Type-Driven Development – Replacing Unit Tests with Types in Typescript

Being explicit about the return type of the function is the most under-utilized feature of TypeScript. At least, that’s true for the way I write my code. When I first started using TypeScript, I was really impressed with the way it inferred the return type of the function, and having these types perpetuate throughout the […]

Generic Higher-Order Functions in TypeScript

As of TypeScript 3.1, the lib.es5.d.ts file provides a couple of predefined types that are very helpful when trying to write generic higher-order functions. In this post, I’m going to show an example of using the Parameters and ReturnType predefined types for just that purpose.

Setting up a Test FTP Server in Node

On a recent project, I had a need to create an FTP connection to a third-party server. Since we had no control over the server, I also wanted to setup a test FTP server that I could use to run our client against to make sure we could connect successfully. It turned out that implementing […]

Using an Int Type in TypeScript

The project I’m working on has a Node.js back end written in TypeScript, with a PostgreSQL database for persistence. We had a production user who encountered an error when the system tried to insert a row into a table that had an integer column in it. The value it was trying to insert was 239.99999999999997, […]

“Understanding TypeScript’s Structural Type System” at Strange Loop 2018

I'm super excited to be giving a talk about TypeScript at Strange Loop this year! The talk, “Understanding TypeScript's Structural Type System,” covers some of the deeper and most exciting ideas at the heart of TypeScript's namesake feature. You can get an overview from the slides. (I'll post a link to the video once it's […]

Creating a Drag-and-Drop File Uploader with React & TypeScript

A while ago, I was working on a project based off the Atomic SPA Starter Kit, which uses TypeScript, React, and GraphQL. One of the features we needed to build was a file upload component that supported dragging and dropping a file from a separate window onto the UI.

Correctly Managing Concurrency in JavaScript

More times than I can count, I’ve found myself needing better concurrency primitives in JavaScript (or TypeScript) applications. Almost anything you might need is possible using the Promise API, but promises are complex, and there are many subtleties that easily manifest bugs.

Migrating an Ejected Create React App to TypeScript

I love Create React App, and I also love TypeScript. That means I really love react-scripts-ts, which is a great way to spin up a new SPA for experimental purposes.

Mocking TypeScript Modules with Sinon

Lately, my team has been looking for better ways to create and maintain mocks in our TypeScript project. In particular, we wanted an easy way to mock out modules that we built using Sinon.JS.

Styling Custom Components in React Native Using TypeScript

I recently ran into an issue with providing style properties to custom React Native components written in TypeScript. When defining the type of the style property, we were using the ViewStyle and TextStyle types provided by React Native. interface Props { textStyle?: TextStyle; viewStyle?: ViewStyle; } class BlogPost extends React.PureComponent<Props> { render() { return ( <View […]

Atomic Spin

Atomic Object’s blog on everything we find fascinating.

TypeScript