Must parameter passing into dispatch function be Object which containt 'type' property in reactjs

i am learning about useReducer in Reactjs. In teaching video or documentation about useReducer Hook, parameter passed into dispatch function is always a regular JavaScript object (which contain type property and other infor helping to set new state in reducer function).

I have a question that passing object as parameter to dispatch function in reactjs is the rule of Reactjs or it is a coding convention of reactjs dev communication. In addition, instead of passing object as parameter to dispatch function, can i pass whatever data's type as i want to dispatch function?

From the Extracting State Logic into a Reducer documentation:

> An action object can have any shape.

> By convention, it is common to give it a string type that describes what happened, and pass any additional information in other fields.

It's a convention, not restrictive nor mandatory.

Here are some best practices:

• Flux Standard Action
• Do Not Put Non-Serializable Values in State or Actions
• Write Actions Using the Flux Standard Action Convention. Prefer using FSA-formatted actions for consistency.

See this test case: double invokes reducer functions

You will find dispatch(1), this test case dispatches a primitive number.

Take a look at the source code, the action will be pass-through to the reducer function here.

React v16.14.0

// ...
const currentState: S = (queue.lastRenderedState: any);
const eagerState = lastRenderedReducer(currentState, action);
// ...