React-Redux, how to change state?

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9 Answers

reduxchangestatereact
90%

Now when we have a store which contains a state tree and a few ways to interact with the state, how can we update application state?,State Tree — A plain JavaScript object which contains whole application state,getState() — Returns the current state of the application.

An action is a plain JavaScript object to keep track of the specific event taking place in the application. What makes it special is a ‘type’ property which is a necessary part of it.

{
   type: "ADD_BOOK_TO_THE_CART"
}
88%

In your reducer, and for all four tries, you are modifying the existing state before returning it.,This results in react-redux, when checking if your state has changed, not to see any changes as both the previous and next states are pointing to the same object.,In your reducer, try returning a brand new array as follows:

In your scenario your initial state could be an array as such:

[{
   href: '/',
   active: true
}]
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72%

Based on this information, we should now be able to describe the kinds of values we need to have inside our Redux state:,One of the goals of Redux is to make your code predictable. When a function's output is only calculated from the input arguments, it's easier to understand how that code works, and to test it.,Let's start by figuring out the initial business requirements for this application:

ReactDOM.render(  <Provider store={store}>    <App />  </Provider>,  document.getElementById('root'))
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65%

Step 2 — Creating Actions and Reducers , Step 1 — Setting Up a Store ,Your Redux store is now all set up and ready for changes. In the next step you’ll dispatch actions from a component to update the data.

Pretag
 Pretag team - issue, fix, solve, resolve
75%

If you change state at all, replace it (more on this later).,It can be helpful to think of actions as "reports" or news stories. They don't describe intent, they describe facts that happened.,To do this, we follow the immutability rule: “If you change it, replace it.” So what does that look like in code?

{
   type: 'FETCH_USERS_STARTED'
}
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store.dispatch(action) - Dispatch an action to change the state.,store.getState() - Returns the current state object tree.,An action creator is a function that returns an object representing an action that can be dispatched to the Redux store. In this app we have two actions:

I am using the spread operator in the code. This basically makes it possible to copy an array by doing:

const copy = [...original];
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22%

To mutate(change) the redux state, you need to dispatch an action. Recall that an action is the 2nd parameter that gets passed to your reducer. An action is an object that tells your reducer what happened (e.g. toggle, click, etc.)., Dispatching Actions to Change State , Learn The Fundamentals of Redux Introduction Displaying the State Dispatching Actions to Change State

render() {
+ const onClick = () => store.dispatch({ type: 'TOGGLE' });
  return (
    <div>
      <h1>To-dos</h1>
      <div>
        Learn Redux&nbsp;
        <input
          type="checkbox"
          checked={!!this.state.checked}
+         onClick={onClick} />
      </div>
      {
        this.state.checked ? (<h2>Done!</h2>) : null
      }
    </div>
  );
}
60%

Let’s discuss how to use react state management using react hooks and redux,useState is a Hook that Lets you add React state to function components. Example: Declaring a State Variable in class and initialize count state with 0 by setting this.state to {count:0}.,The state which is managed in this reducer is an array of items:

Pretag
 Pretag team - issue, fix, solve, resolve
48%

To update the state you need to create a reducer, as shown below.,When working on React-Redux apps, you will come across many use cases where you have to pass and manage data between components. In this guide, you will learn how to handle parent-child data relationships in Redux.,As mentioned earlier, you cannot change the state object or the global store directly. To change the state object, you need to use actions and reducers. An action is simply a JavaScript object that passes information to reducers, and reducers are pure functions that return an updated state based on the current action that was dispatched.

1
const initialState = {
   2 parentCounter: 0,
   3 childCounter: 0,
   4
};
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