How to avoid importScripts is not defined in React

If you attempt to initialize Progressier's default service worker into your React project, you may encounter the following issue when building your app with React:

It's a matter of context. When the code of the worker is executed in the context of the actual service worker — where importScripts does indeed exist — everything will be fine. However, if you use React with ESLint or other code analysis programs, the existence of that function may be verified in a different context — one where importScripts doesn't exist.

If you use ESLint, add the following line of code right before you invoke the importScripts function:

Alternatively, you could conditionally invoke importScripts after making sure importScripts is defined as follows:

This is the default Progressier service worker:
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This is the amended version: