Which RUM snippet variant is right for me?

There are three RUM snippet variants available:

• Most Compatible (Default)
• Modern Browsers (ES2015)
• Cutting Edge (ES2020)

In most cases we recommend using the Most Compatible (Default) variant. This variant is made to work with as many web browsers as possible, even old Internet Explorer versions. The other two variants offer slightly smaller bundle sizes, at the cost of decreased legacy browser support.

Most Compatible (Default)

This variant is compiled to ECMAScript 5 and contains some polyfills for legacy browsers. Please note that modern metrics like Largest Contentful Paint (LCP) and other Web Vitals metrics cannot be polyfilled.

Modern Browsers (ES2015)

This variant is compiled to ECMAScript 2015 (commonly called "ES6") and does not contain any polyfills. This variant is roughly 6% smaller than the "Most Compatible" variant. At the time of writing, ES6 is supported by 95% of browsers according to Can I Use.

Cutting Edge (2020)

This variant is compiled to ECMAScript 2020 and does not contain any polyfills. This variant is roughly 7% smaller than the "Most Compatible" variant.