Next.js 16 packs obsolete polyfills

[tkrotoff]

Goals

Next.js 16 default supported browsers are Chrome 111+, Edge 111+, Firefox 111+, Safari 16.4+

(https://github.com/vercel/next.js/blob/v16.0.2-canary.7/packages/next/src/shared/lib/modern-browserslist-target.js)

Next.js 16 also packs some polyfills: https://github.com/vercel/next.js/blob/v16.0.2-canary.7/packages/next-polyfill-nomodule/src/index.js

Most of those polyfills can be removed, examples:

• Array.find() is supported by all browsers since 2015
• Object.assign() is supported by all browsers since 2015
• fetch is supported by all browsers since 2017 so no need for whatwg-fetch
• Array.at() is supported by all browsers listed
• ...

Proposal

Next.js polyfills should be on par with Next.js supported browsers

If a user wants to support older browsers then he has to provide those polyfills

[icyJoseph]

Those in the link are loaded with the nomodule attribute though, https://developer.mozilla.org/en-US/docs/Web/API/HTMLScriptElement/noModule - so the browser doesn't download them unless necessary.

In this other polyfill, https://github.com/vercel/next.js/blob/v16.0.2-canary.7/packages/next-polyfill-module/src/index.js there's a couple that could be dropped though

[tkrotoff]

Thanks for the clarification.

Next.js doc (https://nextjs.org/docs/architecture/supported-browsers) explains:

Polyfills

We inject widely used polyfills, [...]

With a link to next-polyfill-nomodule hence my mistake. Doc could be clarified on this, it doesn't talk about next-polyfill-module.

I feel next-polyfill-nomodule should be obsoleted: script type="module" is supported by all browsers since at least 2018 (so 7 years)

[icyJoseph]

That section does end with:

In addition, to reduce bundle size, Next.js will only load these polyfills for browsers that require them. The majority of the web traffic globally will not download these polyfills.

I'll put it on my backlog to further expand here.

[antongunkin]

Have the same concern mostly because of this: