JavaScript introduced symbols in ES6 as a way to prevent property name collisions. As an added bonus, symbols also provide a way to simulate private properties in 2015-2019 JavaScript.

The TC39 async iterators proposal that brought for/await/of to JavaScript also introduced the concept of an async generator function. Now, JavaScript has 6 distinct types of functions:

Puppeteer is Google's official npm module for controlling Chrome from Node.js. Using Puppeteer, you can open up a Chrome browser, navigate to an arbitrary page, and interact with the page by executing arbitrary JavaScript. Here's a short list of what you can do with Puppeteer:

Error handling in async/await causes a lot of confusion. There are

Async functions were introduced in the 2017 edition of the JavaScript language spec. Async functions differ from normal JavaScript functions in 2 major ways:

Mongoose 5.6.0 was released last week. This new release has 12 new features, 2 performance improvements, and several docs improvements. The most interesting new feature is immutable properties. The idea is that marking a property as immutable means that property cannot change after the document is created.

JavaScript arrays are an essential part of the language. Fundamentally, an array is a value that stores an ordered list of other values. But JavaScript arrays come with a lot of nuances and surprises. In this article, I'll provide an overview of what you need to know about JavaScript arrays.

Puppeteer is a powerful automation library for Google Chrome. With Puppeteer, you can launch a Chrome browser that you have full control over from Node.js. This makes UI testing easy: your client-side app runs in a real browser, no need to worry about the painful quirks of Jest attempting to mimic a browser in Node.js. Puppeteer runs in headless mode by default, which means the Chrome window isn't visible. But you can still take screenshots in headless mode, or you can disable headless mode and watch your tests click through your app.