Using the Effect Hook – React (2023)

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  • Synchronizing with Effects
  • You Might Not Need an Effect
  • useEffect

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Hooks are a new addition in React 16.8. They let you use state and other React features without writing a class.

The Effect Hook lets you perform side effects in function components:

import React, { useState, useEffect } from 'react';function Example() { const [count, setCount] = useState(0); // Similar to componentDidMount and componentDidUpdate: useEffect(() => { // Update the document title using the browser API document.title = `You clicked ${count} times`; }); return ( <div> <p>You clicked {count} times</p> <button onClick={() => setCount(count + 1)}> Click me </button> </div> );}

This snippet is based on the counter example from the previous page, but we added a new feature to it: we set the document title to a custom message including the number of clicks.

Data fetching, setting up a subscription, and manually changing the DOM in React components are all examples of side effects. Whether or not you’re used to calling these operations “side effects” (or just “effects”), you’ve likely performed them in your components before.


If you’re familiar with React class lifecycle methods, you can think of useEffect Hook as componentDidMount, componentDidUpdate, and componentWillUnmount combined.

There are two common kinds of side effects in React components: those that don’t require cleanup, and those that do. Let’s look at this distinction in more detail.

Effects Without Cleanup

Sometimes, we want to run some additional code after React has updated the DOM. Network requests, manual DOM mutations, and logging are common examples of effects that don’t require a cleanup. We say that because we can run them and immediately forget about them. Let’s compare how classes and Hooks let us express such side effects.

Example Using Classes

In React class components, the render method itself shouldn’t cause side effects. It would be too early — we typically want to perform our effects after React has updated the DOM.

This is why in React classes, we put side effects into componentDidMount and componentDidUpdate. Coming back to our example, here is a React counter class component that updates the document title right after React makes changes to the DOM:

class Example extends React.Component { constructor(props) { super(props); this.state = { count: 0 }; } componentDidMount() { document.title = `You clicked ${this.state.count} times`; } componentDidUpdate() { document.title = `You clicked ${this.state.count} times`; } render() { return ( <div> <p>You clicked {this.state.count} times</p> <button onClick={() => this.setState({ count: this.state.count + 1 })}> Click me </button> </div> ); }}

Note how we have to duplicate the code between these two lifecycle methods in class.

This is because in many cases we want to perform the same side effect regardless of whether the component just mounted, or if it has been updated. Conceptually, we want it to happen after every render — but React class components don’t have a method like this. We could extract a separate method but we would still have to call it in two places.

(Video) Learn useEffect In 13 Minutes

Now let’s see how we can do the same with the useEffect Hook.

Example Using Hooks

We’ve already seen this example at the top of this page, but let’s take a closer look at it:

import React, { useState, useEffect } from 'react';function Example() { const [count, setCount] = useState(0); useEffect(() => { document.title = `You clicked ${count} times`; }); return ( <div> <p>You clicked {count} times</p> <button onClick={() => setCount(count + 1)}> Click me </button> </div> );}

What does useEffect do? By using this Hook, you tell React that your component needs to do something after render. React will remember the function you passed (we’ll refer to it as our “effect”), and call it later after performing the DOM updates. In this effect, we set the document title, but we could also perform data fetching or call some other imperative API.

Why is useEffect called inside a component? Placing useEffect inside the component lets us access the count state variable (or any props) right from the effect. We don’t need a special API to read it — it’s already in the function scope. Hooks embrace JavaScript closures and avoid introducing React-specific APIs where JavaScript already provides a solution.

Does useEffect run after every render? Yes! By default, it runs both after the first render and after every update. (We will later talk about how to customize this.) Instead of thinking in terms of “mounting” and “updating”, you might find it easier to think that effects happen “after render”. React guarantees the DOM has been updated by the time it runs the effects.

Detailed Explanation

Now that we know more about effects, these lines should make sense:

function Example() { const [count, setCount] = useState(0); useEffect(() => { document.title = `You clicked ${count} times`; });}

We declare the count state variable, and then we tell React we need to use an effect. We pass a function to the useEffect Hook. This function we pass is our effect. Inside our effect, we set the document title using the document.title browser API. We can read the latest count inside the effect because it’s in the scope of our function. When React renders our component, it will remember the effect we used, and then run our effect after updating the DOM. This happens for every render, including the first one.

Experienced JavaScript developers might notice that the function passed to useEffect is going to be different on every render. This is intentional. In fact, this is what lets us read the count value from inside the effect without worrying about it getting stale. Every time we re-render, we schedule a different effect, replacing the previous one. In a way, this makes the effects behave more like a part of the render result — each effect “belongs” to a particular render. We will see more clearly why this is useful later on this page.


Unlike componentDidMount or componentDidUpdate, effects scheduled with useEffect don’t block the browser from updating the screen. This makes your app feel more responsive. The majority of effects don’t need to happen synchronously. In the uncommon cases where they do (such as measuring the layout), there is a separate useLayoutEffect Hook with an API identical to useEffect.

Effects with Cleanup

Earlier, we looked at how to express side effects that don’t require any cleanup. However, some effects do. For example, we might want to set up a subscription to some external data source. In that case, it is important to clean up so that we don’t introduce a memory leak! Let’s compare how we can do it with classes and with Hooks.

Example Using Classes

In a React class, you would typically set up a subscription in componentDidMount, and clean it up in componentWillUnmount. For example, let’s say we have a ChatAPI module that lets us subscribe to a friend’s online status. Here’s how we might subscribe and display that status using a class:

class FriendStatus extends React.Component { constructor(props) { super(props); this.state = { isOnline: null }; this.handleStatusChange = this.handleStatusChange.bind(this); } componentDidMount() { ChatAPI.subscribeToFriendStatus(, this.handleStatusChange ); } componentWillUnmount() { ChatAPI.unsubscribeFromFriendStatus(, this.handleStatusChange ); } handleStatusChange(status) { this.setState({ isOnline: status.isOnline }); } render() { if (this.state.isOnline === null) { return 'Loading...'; } return this.state.isOnline ? 'Online' : 'Offline'; }}

Notice how componentDidMount and componentWillUnmount need to mirror each other. Lifecycle methods force us to split this logic even though conceptually code in both of them is related to the same effect.


(Video) Full React Tutorial #14 - useEffect Hook (the basics)

Eagle-eyed readers may notice that this example also needs a componentDidUpdate method to be fully correct. We’ll ignore this for now but will come back to it in a later section of this page.

Example Using Hooks

Let’s see how we could write this component with Hooks.

You might be thinking that we’d need a separate effect to perform the cleanup. But code for adding and removing a subscription is so tightly related that useEffect is designed to keep it together. If your effect returns a function, React will run it when it is time to clean up:

import React, { useState, useEffect } from 'react';function FriendStatus(props) { const [isOnline, setIsOnline] = useState(null); useEffect(() => { function handleStatusChange(status) { setIsOnline(status.isOnline); } ChatAPI.subscribeToFriendStatus(, handleStatusChange); // Specify how to clean up after this effect: return function cleanup() { ChatAPI.unsubscribeFromFriendStatus(, handleStatusChange); }; }); if (isOnline === null) { return 'Loading...'; } return isOnline ? 'Online' : 'Offline';}

Why did we return a function from our effect? This is the optional cleanup mechanism for effects. Every effect may return a function that cleans up after it. This lets us keep the logic for adding and removing subscriptions close to each other. They’re part of the same effect!

When exactly does React clean up an effect? React performs the cleanup when the component unmounts. However, as we learned earlier, effects run for every render and not just once. This is why React also cleans up effects from the previous render before running the effects next time. We’ll discuss why this helps avoid bugs and how to opt out of this behavior in case it creates performance issues later below.


We don’t have to return a named function from the effect. We called it cleanup here to clarify its purpose, but you could return an arrow function or call it something different.


We’ve learned that useEffect lets us express different kinds of side effects after a component renders. Some effects might require cleanup so they return a function:

 useEffect(() => { function handleStatusChange(status) { setIsOnline(status.isOnline); } ChatAPI.subscribeToFriendStatus(, handleStatusChange); return () => { ChatAPI.unsubscribeFromFriendStatus(, handleStatusChange); }; });

Other effects might not have a cleanup phase, and don’t return anything.

 useEffect(() => { document.title = `You clicked ${count} times`; });

The Effect Hook unifies both use cases with a single API.

If you feel like you have a decent grasp on how the Effect Hook works, or if you feel overwhelmed, you can jump to the next page about Rules of Hooks now.

Tips for Using Effects

We’ll continue this page with an in-depth look at some aspects of useEffect that experienced React users will likely be curious about. Don’t feel obligated to dig into them now. You can always come back to this page to learn more details about the Effect Hook.

Tip: Use Multiple Effects to Separate Concerns

One of the problems we outlined in the Motivation for Hooks is that class lifecycle methods often contain unrelated logic, but related logic gets broken up into several methods. Here is a component that combines the counter and the friend status indicator logic from the previous examples:

class FriendStatusWithCounter extends React.Component { constructor(props) { super(props); this.state = { count: 0, isOnline: null }; this.handleStatusChange = this.handleStatusChange.bind(this); } componentDidMount() { document.title = `You clicked ${this.state.count} times`; ChatAPI.subscribeToFriendStatus(, this.handleStatusChange ); } componentDidUpdate() { document.title = `You clicked ${this.state.count} times`; } componentWillUnmount() { ChatAPI.unsubscribeFromFriendStatus(, this.handleStatusChange ); } handleStatusChange(status) { this.setState({ isOnline: status.isOnline }); } // ...
(Video) Learn the React useEffect Hook in 24 minutes (for beginners)

Note how the logic that sets document.title is split between componentDidMount and componentDidUpdate. The subscription logic is also spread between componentDidMount and componentWillUnmount. And componentDidMount contains code for both tasks.

So, how can Hooks solve this problem? Just like you can use the State Hook more than once, you can also use several effects. This lets us separate unrelated logic into different effects:

function FriendStatusWithCounter(props) { const [count, setCount] = useState(0); useEffect(() => { document.title = `You clicked ${count} times`; }); const [isOnline, setIsOnline] = useState(null); useEffect(() => { function handleStatusChange(status) { setIsOnline(status.isOnline); } ChatAPI.subscribeToFriendStatus(, handleStatusChange); return () => { ChatAPI.unsubscribeFromFriendStatus(, handleStatusChange); }; }); // ...}

Hooks let us split the code based on what it is doing rather than a lifecycle method name. React will apply every effect used by the component, in the order they were specified.

Explanation: Why Effects Run on Each Update

If you’re used to classes, you might be wondering why the effect cleanup phase happens after every re-render, and not just once during unmounting. Let’s look at a practical example to see why this design helps us create components with fewer bugs.

Earlier on this page, we introduced an example FriendStatus component that displays whether a friend is online or not. Our class reads from this.props, subscribes to the friend status after the component mounts, and unsubscribes during unmounting:

 componentDidMount() { ChatAPI.subscribeToFriendStatus(, this.handleStatusChange ); } componentWillUnmount() { ChatAPI.unsubscribeFromFriendStatus(, this.handleStatusChange ); }

But what happens if the friend prop changes while the component is on the screen? Our component would continue displaying the online status of a different friend. This is a bug. We would also cause a memory leak or crash when unmounting since the unsubscribe call would use the wrong friend ID.

In a class component, we would need to add componentDidUpdate to handle this case:

 componentDidMount() { ChatAPI.subscribeToFriendStatus(, this.handleStatusChange ); } componentDidUpdate(prevProps) { // Unsubscribe from the previous ChatAPI.unsubscribeFromFriendStatus(, this.handleStatusChange ); // Subscribe to the next ChatAPI.subscribeToFriendStatus(, this.handleStatusChange ); } componentWillUnmount() { ChatAPI.unsubscribeFromFriendStatus(, this.handleStatusChange ); }

Forgetting to handle componentDidUpdate properly is a common source of bugs in React applications.

Now consider the version of this component that uses Hooks:

function FriendStatus(props) { // ... useEffect(() => { // ... ChatAPI.subscribeToFriendStatus(, handleStatusChange); return () => { ChatAPI.unsubscribeFromFriendStatus(, handleStatusChange); }; });

It doesn’t suffer from this bug. (But we also didn’t make any changes to it.)

There is no special code for handling updates because useEffect handles them by default. It cleans up the previous effects before applying the next effects. To illustrate this, here is a sequence of subscribe and unsubscribe calls that this component could produce over time:

// Mount with { friend: { id: 100 } } propsChatAPI.subscribeToFriendStatus(100, handleStatusChange); // Run first effect// Update with { friend: { id: 200 } } propsChatAPI.unsubscribeFromFriendStatus(100, handleStatusChange); // Clean up previous effectChatAPI.subscribeToFriendStatus(200, handleStatusChange); // Run next effect// Update with { friend: { id: 300 } } propsChatAPI.unsubscribeFromFriendStatus(200, handleStatusChange); // Clean up previous effectChatAPI.subscribeToFriendStatus(300, handleStatusChange); // Run next effect// UnmountChatAPI.unsubscribeFromFriendStatus(300, handleStatusChange); // Clean up last effect

This behavior ensures consistency by default and prevents bugs that are common in class components due to missing update logic.

(Video) UseEffect React Hook Explained - React Lifecycle

Tip: Optimizing Performance by Skipping Effects

In some cases, cleaning up or applying the effect after every render might create a performance problem. In class components, we can solve this by writing an extra comparison with prevProps or prevState inside componentDidUpdate:

componentDidUpdate(prevProps, prevState) { if (prevState.count !== this.state.count) { document.title = `You clicked ${this.state.count} times`; }}

This requirement is common enough that it is built into the useEffect Hook API. You can tell React to skip applying an effect if certain values haven’t changed between re-renders. To do so, pass an array as an optional second argument to useEffect:

useEffect(() => { document.title = `You clicked ${count} times`;}, [count]); // Only re-run the effect if count changes

In the example above, we pass [count] as the second argument. What does this mean? If the count is 5, and then our component re-renders with count still equal to 5, React will compare [5] from the previous render and [5] from the next render. Because all items in the array are the same (5 === 5), React would skip the effect. That’s our optimization.

When we render with count updated to 6, React will compare the items in the [5] array from the previous render to items in the [6] array from the next render. This time, React will re-apply the effect because 5 !== 6. If there are multiple items in the array, React will re-run the effect even if just one of them is different.

This also works for effects that have a cleanup phase:

useEffect(() => { function handleStatusChange(status) { setIsOnline(status.isOnline); } ChatAPI.subscribeToFriendStatus(, handleStatusChange); return () => { ChatAPI.unsubscribeFromFriendStatus(, handleStatusChange); };}, []); // Only re-subscribe if changes

In the future, the second argument might get added automatically by a build-time transformation.


If you use this optimization, make sure the array includes all values from the component scope (such as props and state) that change over time and that are used by the effect. Otherwise, your code will reference stale values from previous renders. Learn more about how to deal with functions and what to do when the array changes too often.

If you want to run an effect and clean it up only once (on mount and unmount), you can pass an empty array ([]) as a second argument. This tells React that your effect doesn’t depend on any values from props or state, so it never needs to re-run. This isn’t handled as a special case — it follows directly from how the dependencies array always works.

If you pass an empty array ([]), the props and state inside the effect will always have their initial values. While passing [] as the second argument is closer to the familiar componentDidMount and componentWillUnmount mental model, there are usually better solutions to avoid re-running effects too often. Also, don’t forget that React defers running useEffect until after the browser has painted, so doing extra work is less of a problem.

We recommend using the exhaustive-deps rule as part of our eslint-plugin-react-hooks package. It warns when dependencies are specified incorrectly and suggests a fix.

Next Steps

Congratulations! This was a long page, but hopefully by the end most of your questions about effects were answered. You’ve learned both the State Hook and the Effect Hook, and there is a lot you can do with both of them combined. They cover most of the use cases for classes — and where they don’t, you might find the additional Hooks helpful.

We’re also starting to see how Hooks solve problems outlined in Motivation. We’ve seen how effect cleanup avoids duplication in componentDidUpdate and componentWillUnmount, brings related code closer together, and helps us avoid bugs. We’ve also seen how we can separate effects by their purpose, which is something we couldn’t do in classes at all.

At this point you might be questioning how Hooks work. How can React know which useState call corresponds to which state variable between re-renders? How does React “match up” previous and next effects on every update? On the next page we will learn about the Rules of Hooks — they’re essential to making Hooks work.

(Video) Mastering React's useEffect


How do you use React Hooks effectively? ›

Let's take a look at some best practices for using React Hooks to ensure you're writing clean, efficient, and maintainable code.
  1. Use Hooks as They're Supposed to Be Used. ...
  2. There's an ESLint Plug-In for React Hooks — Use It. ...
  3. useState Can Be Used With Objects Too! ...
  4. Custom Hooks Are Awesome! ...
  5. Don't Use Prop Drilling. ...
  6. Conclusion.

Are React Hooks enough? ›

Hooks are essentially special functions that allow us to hook into React's core features. React Hooks provide an alternative to writing class-based components by allowing us to easily handle state management from functional components.

What does useEffect () do in React? ›

What does useEffect do? By using this Hook, you tell React that your component needs to do something after render. React will remember the function you passed (we'll refer to it as our “effect”), and call it later after performing the DOM updates.

Why not to use useEffect? ›

useEffect Hook is one of the most used Hooks in React, and it always runs on each re-render by default. However, this behaviour of cleaning up or applying the effect after each render can cause performance issues.

What's most important benefit of using React hook? ›

It revolutionizes the way you write components. You can write concise and clearer code. Hooks are simpler to work with and test. Code would appear cleaner and easier to read.

What is the most important hook in React? ›

The useState Hook # The useState hook is the most basic and useful React hook. Like other built-in hooks, this hook must be imported from react to be used in our application. To initialize the state, we must declare both the state and its updater function and pass an initial value.

Why not to use React hooks? ›

The problem. If you create a React component using hooks you are forced to write code in a way that makes it difficult to manage. Look at this code: If you don't know anything about React this may look a little odd to you.

Is React overkill for small apps? ›

Using React can be overkill if the requirements are too simplistic. For example, you need to make a few pages with no dynamic elements or customization. In cases like these, it might suffice to use simple HTML and a bit of JavaScript.

Do I need to learn all React hooks? ›

So yes, you should learn the latest React features. Jump into using hooks right away. They will be the basis of every React app you make.

When should you useEffect? ›

1. useEffect() is for side-effects. A functional React component uses props and/or state to calculate the output. If the functional component makes calculations that don't target the output value, then these calculations are named side-effects.

When should you use useEffect in React? ›

If we perform a side effect directly in our component body, it gets in the way of our React component's rendering. Side effects should be separated from the rendering process. If we need to perform a side effect, it should strictly be done after our component renders. This is what useEffect gives us.

Why is useEffect useful? ›

In React, the useEffect is a very useful hook. The useEffect hook is mainly used to ignore or avoid the unwanted side effects of the class components.

When should you avoid useEffect? ›

There are two common cases in which you don't need Effects:
  • You don't need Effects to transform data for rendering. For example, let's say you want to filter a list before displaying it. ...
  • You don't need Effects to handle user events.

When should you not use Hooks? ›

Don't call Hooks inside loops, conditions, or nested functions. Instead, always use Hooks at the top level of your React function, before any early returns. By following this rule, you ensure that Hooks are called in the same order each time a component renders.

What can I use instead of useEffect? ›

One other situation you might want to use useLayoutEffect instead of useEffect is if you're updating a value (like a ref ) and you want to make sure it's up-to-date before any other code runs. For example: const ref = React.

Are React hooks difficult? ›

React hooks are a constant source of difficult to write and non-deterministic tests. Class components also suffer from the same problems. Now after learning about it I'll never go back to class components. Those aren't the only two options.

Why do people use React hooks? ›

With Hooks, you can extract stateful logic from a component so it can be tested independently and reused. Hooks allow you to reuse stateful logic without changing your component hierarchy. This makes it easy to share Hooks among many components or with the community.

What is the drawback of React hooks? ›

Wrapper hell (caused by design patterns: HOC, render prop, drilling prop) Huge components (that hard to test and maintain, hard to co-locate code) Confusing classes (this keyword, hard to make it reusable)

How do you master React Hooks? ›

When using React Hooks there are a few rules to adhere to: Only call hooks at the top level of a component: You shouldn't use Hooks inside loops, conditions, or nested functions. Instead, always use Hooks at the top level of your React function, before any return keyword.

What are the rules you must follow while using Hooks? ›

There are 3 rules for hooks: Hooks can only be called inside React function components. Hooks can only be called at the top level of a component. Hooks cannot be conditional.

Which are the three common basic React Hooks? ›

But I will focus on some most needed React hook types.
  • State Hook. Let's get started by useState Hook from React. ...
  • Effect Hook. One of the most critical concepts for mastering React today is understanding how the Use Effect Hook works. ...
  • Context Hook.
Aug 11, 2021

Are Hooks faster than classes React? ›

The origin of React hooks

Hooks make React so much better because you have simpler code that implements similar functionalities faster and more effectively. You can also implement React state and lifecycle methods without writing classes.

Why are Hooks better than classes? ›

Easier to decouple logic from UI, making both more reusable. Using hooks, logic and UI are easier to separate. No need for HOC or render props. Hooks do it elegantly with less boilerplate and more intuitive compositions of UI and logic.

What is alternative for Hooks in React? ›

Hooks are part of React and like other comments say you can't use hooks in your API calls. You are looking for a common ground for your components and your API. You may use Session storage for this purpose. Other options like Local storage or Indexed DB will also work.

Why React is not SEO friendly? ›

React gives you a SPA (Single Page Application) which requires Javascript to show the content on the page. The problem is that the Google crawl bot, that scans all the pages on the internet, isn't as good as understanding a page with javascript compared with a page that consists of regular HTML-code.

What are the biggest limitations of React? ›

5 Big Limitations of React
  • It's a Library, Not a Framework. Like other Javascript libraries, React contains pre-written code. ...
  • It Uses JSX. React uses JSX, a syntax extension to JavaScript. ...
  • Does Not Support SEO. React, by design, was not built with SEO in mind. ...
  • Lack of Updated Documentation. ...
  • Fast Development Speed.
Jan 7, 2023

What is the hardest thing to learn in React? ›

State management: React components can have "state," which is data that determines how a component renders and behaves. Managing state can be challenging, especially in larger applications.

How many hours does it take to learn React? ›

For a programmer who is already familiar with HTML and at least one other programming language, learning React will take no more than a single day. React may be learned by a novice programmer in a matter of days. There are more libraries and technologies that may be used with React, such as Redux or Relay.

How long should it take to learn React? ›

Learning React can take anywhere between a couple weeks and a few months. Besides the amount of time you put in regularly, your prior experience with coding will greatly affect how long learning React takes you.

Does useEffect run before every render? ›

The useEffect runs by default after every render of the component. When placing useEffect in our component, we tell React that we want to run the callback as an effect. React will run the effect after rendering and after performing the DOM updates. If we pass only a callback, the callback will run after each render.

Should I use useState or useEffect? ›

The useState hook is used for storing variables that are part of your application's state and will change as the user interacts with your website. The useEffect hook allows components to react to lifecycle events such as mounting to the DOM, re-rendering, and unmounting.

Does useEffect always run on first render? ›

Here we did not pass second argument , so it will run on every render. Here we passed dependency array empty, this useEffect will run only on first render. This useEffect will run on the first render and it will also run on re-rendering if there is a change in xyz compared to the last render.

Is it OK to use multiple useEffect? ›

You can have multiple useEffects in your code and this is completely fine! As hooks docs say, you should separate concerns. Multiple hooks rule also applies to useState - you can have multiple useState in one component to separate different part of the state, you don't have to build one complicated state object.

How do I make useEffect run every time? ›

To solve this use case, you must pass the state variable to the useEffect hook as part of the dependency array. useEffect(() => { // Side Effect }, [state]); In this case, the side effect will run every time the value of the state variable changes.

Does useEffect always run on Mount? ›

Now, we can see that the second component useEffect is only called when the component is originally mounted and unmounted. This is because once we put count in the dependency array, useEffect is only called on mount, unmount, and when count changes between renders.

Does useEffect trigger a Rerender? ›

Let's take a step back, pause for a moment, and think about what useEffect and useState actually do. Changing state will always cause a re-render. By default, useEffect always runs after render has run.

Why do we fetch data in useEffect? ›

For example, your request might fail, your database might be unreachable, or your logging service might have reached its quota. This is why useEffect is the hook for us - by fetching data, we're making our React component impure, and useEffect provides us a safe place to write impure code.

Why is useEffect used to fetch data? ›

The useEffect hook will make a network request on component render. When that fetch resolves, it will set the response from the server to the local state using the setState function. This, in turn, will cause the component to render so as to update the DOM with the data.

What is the best practice to use function in UseState hook? ›

UseState works just as class component's state

Depending on how frequently your application's data changes, it's a good idea to break state into multiple variables. As a rule of thumb, it's best to keep each state separate so that it's easy to update and submit the data.

Why React Hooks are better than classes? ›

Hooks allow you to use local state and other React features without writing a class. Hooks are special functions that let you “hook onto” React state and lifecycle features inside function components. Important: React internally can't keep track of hooks that run out of order.

Are React Hooks still used? ›

React hooks have been around for some time now, yet many React developers are not actively using them.

Why i don't use React Hooks? ›

The problem. If you create a React component using hooks you are forced to write code in a way that makes it difficult to manage. Look at this code: If you don't know anything about React this may look a little odd to you.

What are the three strategies for writing a hook? ›

There are many different approaches to The Hook, including the following:
  • Use a Quotation. ...
  • Pose an Intriguing Question. ...
  • Show a Statistic. ...
  • Employ an Open-Ended Rhetorical Question or Series of Rhetorical Questions. ...
  • Make a Contrarian Statement. ...
  • Provide Unusual Detail. ...
  • Tell a Story.
Jul 8, 2019

Are React Hooks hard? ›

React hooks - easy to learn, hard to master

They're quite easy to get started with, but they're challenging to master properly – you have to learn to think a bit differently compared to React's traditional class components and lifecycle hooks, and there are certain rules that you have to follow.

Does useEffect run before useState? ›

This useEffect will run only once when the button is clicked. The variable will change from the useState, and will cause the useEffect to run. A couple of things to note about the useEffect are that; the first time it will run is when the component that's using it is mounted.

Why should I use useEffect React? ›

The motivation behind the introduction of useEffect Hook is to eliminate the side-effects of using class-based components. For example, tasks like updating the DOM, fetching data from API end-points, setting up subscriptions or timers, etc can be lead to unwarranted side-effects.

What are the disadvantages of Hooks? ›

Hooks make it easy to extract logic and they make it easy to reuse it. While using class components, it is possible to share code between components which makes it much more troublesome. Unfortunately, they don't allow us to mix old classes of components with themselves.

Do I need to learn all React Hooks? ›

So yes, you should learn the latest React features. Jump into using hooks right away. They will be the basis of every React app you make.

What can I use instead of Useeffect in React? ›

useOnUpdate() This is another useful hook for when we want to trigger an action when the component state changes, and not when the component mounts. You can consider it the ComponentWIllUpdate alternative for functional React. This one - calls the callback each time the state changes, triggering an action.

Is React hooks better than Redux? ›

Redux and React Hooks should be viewed as both complementary and distinct concepts. Redux can be used to assist you manage the application data in projects of greater complexity, even though the new React Hooks additions useContext and useReducer allow you to control the global state.


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