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Updated hooks reference #2524

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Updated hooks reference #2524

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4 changes: 4 additions & 0 deletions content/docs/hooks-reference.md
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Expand Up @@ -286,6 +286,10 @@ function Counter() {
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>React guarantees that `dispatch` function identity is stable and won't change on re-renders. This is why it's safe to omit from the `useEffect` or `useCallback` dependency list.

>Note
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>Unlike reducers in Redux or similar state managing solution, actions in `useReducer` are specific to a component. Hence, it is recommended that you **throw an error in the default switch case**. It can help you track bugs in early stages (for example, mistakes in action references).
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@alexkrolick alexkrolick Oct 31, 2019 •
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Switch case is one way to write a reducer, but there are others, like an object literal.

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>Unlike reducers in Redux or similar state managing solution, actions in `useReducer` are specific to a component. Hence, it is recommended that you **throw an error in the default switch case**. It can help you track bugs in early stages (for example, mistakes in action references).
>Unlike reducers in Redux or similar state managing solution, actions in `useReducer` are specific to a component. Hence, it is recommended that you **treat unknown action types as errors** rather than handling them with a default value. It can help you track bugs in early stages (for example, mistakes in action references).

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@alexkrolick alexkrolick Oct 31, 2019 •
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Also, might be worth mentioning how Flow and Typescript can help prevent dispatching unknown action types.

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@JaffParker JaffParker Oct 31, 2019 •
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I find React docs don't make many references to Typescript, they stay pretty agnostic (although I do agree that it's very helpful). Do you still think it's a good idea to add it? I could work it in.

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@alexkrolick alexkrolick Oct 31, 2019 •
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There are a few and this area is one where a type system can specifically help identify either an unhandled state or runtime error.


#### Specifying the initial state {#specifying-the-initial-state}

There are two different ways to initialize `useReducer` state. You may choose either one depending on the use case. The simplest way is to pass the initial state as a second argument:
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