Thus, it is important to handle each action type separately. Some people seem not to like the switch statement, but it’s basically an if/else for possible values on a single field. Here’s how this is different from the previous example. In this scenario, the user is performing certain actions that influence the state of the application.

  • It sends data from your application to the Redux store and serves as the only way to update the store.
  • Redux is an open-source JavaScript library for managing the application state.
  • Well, an application has its state, which can be a combination of the states of its internal components.

Context is not designed for global state management; rather, Context is for avoiding prop drilling through the component tree. For example, for a checkbox the ‘state’ is a true or false value for whether or not it should be checked. The reducer accepts two arguments—state and action—and it returns a new state.

What Does Redux Do? (And When Should You Use It?)

For example, there’s a contacts variable already created within static-data.js, that will always return a randomly generated list of contacts. Before moving on to building the Sidebar and Main components, first some CSS house-keeping. Make sure that the DOM node where the app is rendered, #root , takes up the entire height of the viewport. We’ll discuss the overall layout of the app, then the design of the app’s state object, then we’ll build out the smaller components. Any time there’s a successful update to the store, the will now be re-rendered with the new state values. Also, you may notice that the App component returns an array.

what does redux do

It helps to manage the state of the app in a single place. It also frames a clear understanding of Redux to the core. In case any project needs a state management tool, Redux is the best option to reap the benefits in the long run.

How to Get Started with Redux

Also, each contact is passed in as a user prop to the User component. Each time the store updates and invokes render , let’s log the state from the store. From a high level, it should be pretty clear that within the Sidebar component, there’s the need to render a list of a user’s contacts. Now, depending on the kind of application you’re building, this can cause very serious problems. For what it’s worth, the process of removing nested entities from your state object and designing it like we’ve done here is called “Normalizing the State Object”. I don’t want you confused in case you see that somewhere else.

KillerFunction will take care of invoking the functions. Let’s see this in practice, and how exactly these reducers are combined for a single purpose. The state returned here is not the state of the entire application. what does redux do All we did was have one reducer manage the entire state updates. Consider the state object of the Hello World app we built earlier. Right now, remove the initial state in the createStore method.

Let me take a step back and explain how reducer composition works again. Even if the Cashier can do all the work effectively, it may be more manageable — and perhaps a better customer experience — to have more than one Cashier in the bank hall. We are rendering a User component within the Sidebar , but this component doesn’t exist yet. Console.log(store.getState()) is the bit you’re familiar with.

what does redux do

Then, we wrap our App component with the Provider function and pass the store as a prop. This makes the Redux store available to all the components inside the App. In Redux, a reducer is a function that takes in the current state of an application and an action as arguments, and returns a new state based on the action. You can think of dispatch as a mail carrier who delivers mail to different departments in a large company. Just like how the mail carrier delivers mail to different departments, dispatch delivers actions to various reducers in your Redux store. Each reducer is like a department in the company that processes the mail and updates its own part of the company’s data.

This does require work, and if the data for a given component hasn’t changed, then re-rendering is likely some wasted effort because the requested UI output would be the same. It is easy to test Redux apps because they rely on pure functions. This means tht tests can simply call a pure function with specific parameters and check if the return value matches the expected result. Redux is strict about how code should be organized, which makes it easier for someone with knowledge of Redux to understand the structure of any Redux application.

what does redux do