As the world builds sites that are more heavily reliant on JavaScript, we sometimes pay for what we send down in ways that we can’t always easily see. Addy Osmani will explain how and why JavaScript is the most expensive resource your site uses today—especially on mobile and lower-end desktops.

Addy will also share tips for fixing JavaScript performance issues so everything loads quicker. A little discipline can help if you want your site to load and be interactive as soon as possible on mobile.

Video:https://www.youtube.com/watch?v=ZKH3DLT4BKw

Objective
Teach developers why JavaScript is the costliest part of their sites and what they can do to optimize this well.

Five Things Audience Members Will Learn:

What the dominant costs of heavy JavaScript are
How median hardware plus heavy JavaScript can impact user-experience
Tips and tricks for reducing the cost of JavaScript, reducing long-tasks and improving the Core Web Vitals metrics
Things frameworks and browsers are doing to try reducing the cost of JavaScript by default.
How new performance metrics can help you reason about where to optimize JavaScript to improve user interactions

First presented at FITC/Web Unleashed