- IE9 which finally allowed you to use modern (at the time) web features (like flexbox) without having to support IE specific hacks.
- ES6 which added a lot of syntax changes to JS to make it much nicer to use (and pretty much killed Coffeescript).
- Popularization of type-checking with Typescript and Flow around 2020 which is almost standard these days.
And of course the frameworks evolved a lot as well, but that was mostly project-specific not so much the platform. Someone doing React doesn't care about Angular2 release.
A lot more than that! Typescript is a passing fad! ;)
The Esc key used to stop animated gifs and cancel AJAX calls, it was like a 'stop the world, lemme get off!' button.
Canvas tag (with desynchronized context), Gamepad API, and Web Audio API made the browser into a full-blown operating environment supportive of game development.
CSS3 - grids, aspect-ratio, media queries, oh my!
Web Workers, ASM.js, and WebAssembly -- what even is web development anymore?!?
Of all of those only CSS3 is actually a big deal for most projects (and only a subset of the new CSS3 features). But yeah the new APIs are great and more power is better. Native video/audio playback/streaming was huge as well, but only for a certain class of applications.
I was just highlighting the stuff that really made a huge difference for everyone. Even if you don't use typescript your deps probably do and your IDE can show type hints.
I use Typescript, but I've found comprehensive JSDoc comments do much of the same thing in the right IDE (JetBrains) without paying any of the build time. So, when I have the choice I just use ES2017 (whichever version that has async/await)
Typescript only ever paid off in-terms of capabilities for me when my dependencies went all-in with the runtime type information - felt a lot like Java development marshalling and unmarshalling JSON to objects. But by then, my build times were turning into molasses.
- IE9 which finally allowed you to use modern (at the time) web features (like flexbox) without having to support IE specific hacks.
- ES6 which added a lot of syntax changes to JS to make it much nicer to use (and pretty much killed Coffeescript).
- Popularization of type-checking with Typescript and Flow around 2020 which is almost standard these days.
And of course the frameworks evolved a lot as well, but that was mostly project-specific not so much the platform. Someone doing React doesn't care about Angular2 release.