For our 21st instalment of the JS Roundabout we will be heading back to Twitter's Soho-based offices.

Firstly, we will be hearing from Leonardo Crespo of Twitter, with a talk entitled 'AST: Awesome Super Tool':

It’s always good to understand how things work under the hood. Not only because it allows you to understand how to properly use things or how things may fail, but also to add that knowledge to your toolkit when needing to solve a problem.

How does Babel work? And ESLint? What about Prettier? Oh, and codemods? They all share a common concept which will unlock a world of possibilities if you understand it: the AST (stands for Abstract Syntax Tree).

Let’s learn a bit about yet another acronym, in order to learn how we can use it to bend the code to our will, and also have fun experimenting.

We will then hear from Jorge Ferreiro of Eventbrite. Jorge will be discussing Web Performance, with a talk entitled 'Web performance: Expectations vs. Reality'

“Why is my website slow?”, “How can I improve the loading time?”, “How does the browser render a website?”, “What techniques can I apply to boost the speed of my website?”.

You will not only learn about the most common performance mistakes in a webpage but also, what the best solutions are and the main trade-offs when it comes to web performance.

We will see in details the three parts that affect your web performance (network requests, browser parsing, and browser rendering), and we will cover everything from loading non-blocking Javascript, reducing bundle sizes, cache content and more techniques.

Pizza and beer/wine/soft drinks will be provided as usual - look forward to seeing you all there!

Agenda:

6:00pm - Arrival, networking, food and drinks!

6:40pm - Leonardo Crespo (Twitter) - 'AST: Awesome Super Tool'

7:20pm - Jorge Ferreiro (Eventbrite) - 'Web Performance: Expectations vs Reality'

7:50pm - Networking and drinks

8:15pm - Pub

Thanks all! Please feel free to spread the word about this meetup on LinkedIn and Twitter! Our handle for both is @JsRoundabout