testdouble.js (AKA td.js) VS node

ESM modules need custom loaders for mocking. Testsouble (https://www.npmjs.com/package/testdouble) was one of the first frameworks to support it AFAIK and a great type-safe option.

Alternative is using testdouble with `td.object()` https://www.npmjs.com/package/testdouble

I’m not sure I manage to follow the author correctly, but to me it seems that by “mock” they strictly refer to external mocking libraries, in the sense of JS’s `testdouble` [1] or Java’s `Mockito` [2]. The fake object as returned by `LoginClient.createNull().getUserInfo(...)` appears to be a “Nullable” for them.

[1] https://www.npmjs.com/package/testdouble

If you need an alternative for mocking, testdouble.js has full ES module support thanks to some excellent work by Gil Tayar.

Let’s see how we could set up a shiny new JavaScript project using the Yarn package manager. We are going to set up nodenv, install Node.js and Yarn, and then initialize a new project that we will then be able to use as a foundation for our further ideas.

Node.js ( https://nodejs.org/ )

Visit the Node.js website and download the latest version of Node.js for your operating system.

Basic knowledge of Node.js and its environment setup. If you don't have Node.js installed on your system, make sure you download and install it from the official Node.js website.

Node.js can be easily installed from its official website. Depending on your operating system, you can choose the Windows, macOS, or Linux version. Node.js packages come with npm (Node Package Manager), which is essential for managing dependencies in your projects.

To get started with Node.js 22.0.0, you can download the latest version from the official Node.js website. For those upgrading from an older version, it is recommended to test your existing applications for compatibility with the new release, particularly if you are using native modules or rely heavily on third-party npm packages.

Node.js (version 10 or higher)

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Before starting a new project in react, you need to make sure that you have NodeJS install on your system. You can download the latest version of node at https://nodejs.org. Follow the instructions on the node website to do the installation.