How do I know which ES6 functions I need to polyfill?

Question

After much hair-pulling with create-react-app, I now understand Babel only polyfills a few ES6 functions and leaves the rest to crash on anything that isn't super-new Chrome.

Now, given that I need to manually add the pertaining polyfills myself, is there a way of just adding all ES6 polyfills in, or do I need to go through every component and node module manually to find every breaking function?

Answer 1

The best strategy personally I found is to compile project for production, deploy it and test everything in a browsers you want your website to support, either by installing them or using virtual machines, or even tools like https://www.browserling.com/ or https://crossbrowsertesting.com/

You could easily inspect your browser console then and google for errors (they're easy to search and find out which polyfill you actually needs)