ECMAScript evolution and support

The version of JavaScript that most developers around the world are familiar with is ES5, which was released in 2009. It included strict mode, accessors, syntax changes, meta-programming, and, most importantly, support for JSON.

Since 2015, ECMAScript, and thus JavaScript, has rapidly evolved. The specification now has a yearly release schedule, meaning that a new version is released each year. Thanks to this evolution, each year, all of the language change proposals that are mature enough get included in the new version of the specification. This follows a trend that we can see throughout the industry to increase the pace at which things evolve. It is very disruptive for large enterprises but is great for innovation.

In 2015, ECMAScript 6 was released and was later renamed ES2015. Since then, ES2016, ES2017, ES2018, and ES2019 have been released in the respective years.

Make sure to stop by Dr. Axel Rauschmayer's blog (http://2ality.com) to learn more. Comparatively, ES2015 was incredibly big compared to the following iterations.

As you can imagine, it takes time for browser vendors and JavaScript engine developers to integrate newly standardized elements of the language. With ES2015, this meant that things such as let, const, classes, and many other features could not be used directly. This led to the increase in popularity of transpilation using tools such as Babel or TypeScript. Basically, the idea is to be able to use the newest features of the specification in your code right now and to transpile it so that it can run in environments that don't support those features just yet.