The Cost Of JavaScript In 2018

Building interactive sites can involve sending JavaScript to your users. Often, too much of it. Have you been on a mobile page that looked like it had loaded only to tap on a link or tried to scroll and nothing happens?

Byte-for-byte, JavaScript is still the most expensive resource we send to mobile phones, because it can delay interactivity in large ways.

JavaScript processing times for CNN.com as measured by WebPageTest (src). A high-end phone (iPhone 8) processes script in ~4s. Compare to th...