A week ago me and two of my front-end colleagues went to Hungary. We visited JSConf in Budapest at the stunning Urania National Movie theater. Here are my takeaways! So, here we go: a collection of things I think were noticeable in the talks given at JSConf. See it as a super-dense list of information for you to scan. If speakers mentioned something on the web, I've added links to it so you can find it more easily :)

"Staying up to date is part of your job", visiting conferences and meetups really help staying up to speed with the fast paced developments in front-end.
You should take a look at the Intersection Observer API! With it you can check if an element in your DOM is in the visible viewport. Great for use on lazy loading images, for example.
The MutationObserver can help you detect changes in the DOM.
If you want to measure performance of your site / app, the Navigation Timing API can be something you want to use. Also the Resource Timing API and User Timing API are API's you should take a look at.
Tip: watch the video of 'Leveraging the Metrics that Most Affect User Experience' from Google I/O 2017 to learn more about improving a crucial aspect for your users: performance.
Element queries? Well, almost, and it's called the ResizeObserver. It checks if an element's size has changed. Doesn't work with CSS transforms though.
Check the video 'Help, I'm stuk in an event-loop' if you want to know more about the Event loop in Javascript.

About the Impostor Syndrome: "The reason we struggle with insecurity is because we compare our 'behind-the-scenes' with everyone else's 'highlight reel'". It's like Facebook; you may be not feeling so well but on Facebook everybody is only showing them having a great time.
WebAssembly (wasm) is a direct successor to asm.js, which could be used to run software written in for example C as web applications. Recompiling needed to be done for all chipsets, wasm changes that since it's a general purpose virtual architecture. It's an open standard, low-level binary format meant for computers. It allows you to, for example, run the Unreal Engine in your browser.
If you want a deeper understanding of what the compilation to wasm does, check out the WebAssembly Explorer, where you can see the generated machine code.
Web Assembly doesn't replace Javascript. In fact, you could leverage both to make hybrid sites/apps.
Browser support for WebAssembly has gone from 0 to a all modern browsers within a year!
Check out some of the use cases for WebAssembly! It's fascinating to see what impact WebAssembly has on the web platform.
Are you working on animations for the web? Check out what the Web Animations API can do for you!

"Accessibility doesn't just happen, you need to make it happen!". Start making it happen now by for example installing pa11y. You could put pa11y in your continuous development pipeline and make it break if it finds errors.
Check out the free Udacity Web Accessibility course by Google!
WebRTC is basically plugin-free realtime communication. for the web. Governments are increasing their grip on the centralized internet. WebRTC (which stands for Web Real-Time Communications) can be used to create a network made form small nodes without a centralized system that can be monitored or blocked. This could lead to a distributed Wikipedia, which no government could block.
How do you do code reviews at your company? Discuss this with your colleagues! Chances are your reviews aren't as effective as they could be. You could for example check out the code and let the person who made it explain it, offering junior developers an opportunity to learn while reviewing.
We're all human first, and developer second. Recognise possible signs something is going on with a colleague. A simple question like 'how are you doing?' can turn around someone's week.

Whew, that's a lot of information! We've had a great time learning about these topics, and I hope you have too while clicking through this list!

Accessibility Overview

Indivirtual @ JSConf Budapest