How to find out that the user does not support the current code on the site?

Question

JavaScript

The essence of the problem is this. Now the site has been updated and it turns out that users using opera mini and other old browsers see an error on the site. i.e. this technology stack is simply not supported by these users. the whole site is on react, requests go through fetch. all sorts of polyfills have already been delivered. that is, you need to somehow determine that the user has an old phone and transfer it to another version of the site. The difficulty is that I don’t know by what parameter to evaluate that the user has an old phone

Answer 1

if (!window.fetch) {
  console.log('тебе с нами не по дороге, старый телефон!')
  location.href = 'https://www.google.com/search?q=купи+телефон'
}

Approximately according to the same principle, you can check the rest of the features. And it's better than figuring out the phone model. On many old phones, you can also install new browsers.

Answer 2

If it's only a fetch, it's enough to make a polyyil fetch

Answer 3

You can google "outdated browser detection react".

Answer 4

I can recommend collecting errors using https://www.google.com/analytics/ then you will know on which devices and what specific errors.