How to type Redux actions and Redux reducers in TypeScript?

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problem ：

What is the best way to cast the action parameter in a redux reducer with typescript? On the redux reducer Medium conversion action What is the best way to use parameters ？There will be multiple action interfaces that can occur that all extend a base interface with a property type. There may be multiple operation interfaces , They all extend the basic interface with attribute types .The extended action interfaces can have more properties that are all different between the action interfaces. The extended action interface can have more properties , These properties are different between action interfaces .Here is an example below: Here is an example ：

interface IAction {    type: string}interface IActionA extends IAction {    a: string}interface IActionB extends IAction {    b: string}const reducer = (action: IAction) {    switch (action.type) {        case 'a':            return console.info('action a: ', action.a) // property 'a' does not exists on type IAction        case 'b':            return console.info('action b: ', action.b) // property 'b' does not exists on type IAction             }}

The problem is that action needs to be cast as a type that has access to both IActionA and IActionB so the reducer can use both action.a and action.a without throwing an error. The problem is action Need to be converted to be accessible IActionA and IActionB The type of , such reducer You can use it at the same time action.a and action.a Instead of throwing errors .

I have several ideas how to work around this issue: I have a few ideas on how to solve this problem ：

1. Cast action to any . take action Project to any .
2. Use optional interface members. Use optional interface members .

example: Example ：

interface IAction {    type: string    a?: string    b?: string}

1. Use different reducers for every action type. Use different reducers for each action type .

What is the best way to organize Action/Reducers in typescript? Organize in typescript Action/Reducers What's the best way to ？Thank you in advance! Thank you first ！

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Solution ：

Reference resources ： https://stackoom.com/en/question/2OsYD