[Docs] Sample when intruducing Redux Toolkit may cause confusion

[muyangren918]

What docs page needs to be fixed?

• What Does the Redux Core Do?:
• https://redux.js.org/introduction/why-rtk-is-redux-today:

What is the problem?

The todoToggled function before using Redux Toolkit accepts id as parameter and returns an object inside which payload property is also an object. The object has id as the only property and the id parameter as its value. So within reducer, payload.id is used when comparing with todo.id.
However, I guess the todoToggled function after using Redux Toolkit(The auto generated one) differs so this time payload itself is used when comparing with todo.id. It seems that the auto generated one's behavior is that the parameter is just assigned to payload, which means if you call generated todoToggled function like todoToggled(123) then you get {type: TODO_TOGGLED, payload: 123} as action, and if todoToggled({id: 123}) then you get {type: TODO_TOGGLED, payload: {id: 123}}, without any magic.

A few days ago, a friend asked me why the latter is using payload itself to compare with todo.id. "It's hard to beleive that the offical site sometimes alse make mistake." She told. I aggred with her at the beginning and finally I realized that the sample after using Redux Toolkit may suppose actual function calling is todoToggled(123). We are both foreign beginners to Redux. I think there may be an confusing sample design to beginners on this page. I suggest the sample before using Redux Toolkit should be modified to make sure the right place is only focused on. Besides, when toggling todo, the id paratemer is only needed.

What should be changed to fix the problem?

Change the todoToggled function to return an object of {type: TODO_TOGGLED, payload: id} and change the according reducer to todo.id !== action.payload when comparing todos.

[timdorr]

We don't want to imply that the payload has to be a simple, scalar type. It can be more complex, so that you can pass multiple values over to your reducer. The action creator accepts a simple input as a convenience, but also so you can self-document the code with the parameter names and types. When you start to add TypeScript, this becomes a lot more obvious.

[markerikson]

Eh, I think the original complaint here is just that there's a mismatch in logic and usage between the "handwritten" snippet and the "RTK" snippet, which makes it feel like they're doing something different. Ultimately they both compare vs the ID, it's whether the ID is the payload or is in a nested field.

Simplest tweak would be to remove the curly braces and the .id from the handwritten example.

[timdorr]

Oh, I didn't scroll down the page far enough... 🤦‍♂️

Yeah, that should be synced up. @muyangren918 Can you make a PR for this?

[muyangren918]

Thank you for quick response. I made a PR.