ECMAScript 6 compatibility table VS browserslist

http://kangax.github.io/compat-table/es6/

This page lists features from es6 (and newer versions linked at the top) along with compliance to the spec. First column is the current browser, second is babel+corejs polyfills.

Overall, babel gets about 70% of the way there.

Case in point: Tail Call Optimization has been part of the JS spec since ES6, but remains completely unimplemented in all mainstream browsers/engines besides Safari[1]. For all but the most predictable inputs, you're pretty much forced to use loops where recursion would otherwise be preferable.

Additional case in point: async Iterables cannot be processed as a piped stream. You must use the for await construct, which is a shame considering the FP niceties that the Array type already provides for more traditional lists. Once again, you are forced to use an imperative construct unless you specifically want to defeat the purpose of using an Iterable in the first place by trying to convert it into an Array (... and potentially choking in the process, I might add!).

[1]: https://kangax.github.io/compat-table/es6/

Eventually the browsers started racing to near-full ES6 compatibility. I remember following ES6 progress in realtime with articles and with compatibility tables http://kangax.github.io/compat-table/es6/ . But many people are acting like that either didn't happen, or like it was a one and done thing (despite the ESNext naming shift to avoid the focus on numbers). So we see people just hand-waving away the importance of polyfills like in this gem:

> https://kangax.github.io/compat-table/es6/

Oh man this was a rough one both for FF and Chrome but Chrome did perform better slightly on cursory glance.

Thanks for providing these links, they're definitely a good rule of thumb benchmarks to test new browsers

Javascript / CSS language syntax: can see availability for Javascript here - https://kangax.github.io/compat-table/es6/

I say this as a JS user, but there is no singular JavaScript (realistically, it's not even JavaScript but instead ECMAScript). There is no one place to go that lays out all of what the language can or can't do the way PHP and Python do. The ECMAScript board makes recommendations, then the browsers and runtimes implement features of the recommendations. This site does a good job laying out which features are implemented for browsers and runtimes based on the flavor of the ECMAScript standard. This unique experience can be especially frustrating for someone learning JavaScript and coming from another language that does not have this problem.

https://kangax.github.io/compat-table/es6/ has a column for "current browser"

Not these days, where most people are using evergreen browsers and iOS users upgrade very quickly.

Take a look at the defaults for browserslist, for example:

https://browsersl.ist/#q=defaults

It just barely supports Safari 15, on iOS only, and that’s likely to go away imminently because it’s under 1% usage.

browserslist

We compile JS only for modern browsers. The list of default browsers in Next can be overridden in your browserslist.

In the latest versions of Next.js, targeting specific browsers or features is a breeze using the Browserslist configuration in your package.json file. The latest version of Next.js (v13) uses the following configuration by default:

For a more general answer to browser support, check out https://github.com/browserslist/browserslist. That seems to be standard tool to help you with that.

As someone else pointed out, you're overestimating Chrome/ium's market share.

Regardless, after the web.dev/baseline announcement, I looked at Browslerlist and one of our site's analytics and it is shocking how many people are not using the last two versions of evergreen browsers. There is a long tail of browser versions in those stats.

https://browsersl.ist

The way folks handle this in production is with browserslist, which lets you query on different things you want to support: https://github.com/browserslist/browserslist. This in turn tells other parts of your tooling what language features to transpile for production.

I imagine tools could be built on top of that which do what you’re asking too

# .browserslist.rc # Babel Preset configuration # -------------------------- # Defines web-browser compatibility parameters for Babel to transpile your JS code. # This configuration is used by babel.config.js. # More information in here. # https://github.com/browserslist/browserslist # Support browsers with a market share higher than 5% >10%