Can someone please explain how the initializeComponentRef utility works?

[swvickers]

The team I'm on has been seeing uncaught exceptions bubbling up from this function and after reviewing the implementation I can't quite grasp how it's expected to work.

Utility in question: https://github.com/microsoft/fluentui/blob/master/packages/utilities/src/initializeComponentRef.ts

It seems to be "extending" a given react component by wrapping some react component lifecycle methods.

The part I'm not understanding in particular though is how the lifecycle functions in initializeComponentRef.ts expect as their first argument the "this" context.
As best I could tell from the "extendComponent" and "appendFunction" utilities, these lifecycle methods should have the same signature as the React lifecycle methods, which do not receive the "this" context as their first argument.

Thanks.

[swvickers]

Ah, my confusion came from not being aware of the handling of "this" as a fake argument parameter which is solely used for type hinting. Described here https://www.typescriptlang.org/docs/handbook/2/functions.html#declaring-this-in-a-function.

The "this" argument is removed from the transpiled output which means the "prevProps" argument is the actual first argument, as expected.