How to update dropdown list field based on another dropdown list in reactjs redux-CodePudding

I'm completely new to coding in reactjs and I'm using MERN stack and still trying to understand redux store. So basic functions I understand but let's say I have a country and city dropdown lists, how can I approach this using actions, reducers, and the component?

CodePudding user response：

I would have the redux state look like this:

{
   countries: {
      "USA": ["New York", "Los Angeles", ...],
      "United Kingdom": ["London", "Manchester", ...],
   },
   selectedCountry: "USA"
}

Then you can have some code that extracts the list of cities based on the selectedCountry, and an action that changes the selectedCountry based on the onChange of a Select element.