1- Put the state into the parent of them(not recommended for 4 layer parent-child). 2- Use useContext and useRducer(or useState) together. Most of the answers given previously are for React.Component-based designs. If you are using useState in the recent upgrades of the React library, then follow this answer. Whenever you require to communicate between a child to the parent at any level down, then it's better to make use of context. In the parent component define the context that can be invoked by the child, such as:
class Parent extends React.Component {
constructor(props) {
super(props)
// Bind the this context to the handler function
this.handler = this.handler.bind(this);
// Set some state
this.state = {
messageShown: false
};
}
// This method will be sent to the child component
handler(id) {
this.setState({
messageShown: true,
id: id
});
}
// Render the child component and set the action property with the handler as value
render() {
console.log(this.state);
return (
<div>
<Child action={this.handler} />
<div>{this.state.id}</div>
</div>
);
}
}
class Child extends React.Component {
render() {
return (
<div>
{/* The button will execute the handler function set by the parent component */}
<button onClick={() => this.props.action(1)} > button </button>
</div>
)
}
}
ReactDOM.render(<Parent />, document.getElementById('main'));
For child-parent communication you should pass a function setting the state from parent to child, like this
class Parent extends React.Component {
constructor(props) {
super(props)
this.handler = this.handler.bind(this)
}
handler() {
this.setState({
someVar: 'some value'
})
}
render() {
return <Child handler = {this.handler} />
}
}
class Child extends React.Component {
render() {
return <Button onClick = {this.props.handler}/ >
}
}
This is how to do it with the new useState hook.
Method - Pass the state changer function as a props to the child component and do whatever you want to do with the function:
import React, {useState} from 'react';
const ParentComponent = () => {
const[state, setState]=useState('');
return(
<ChildComponent stateChanger={setState} />
)
}
const ChildComponent = ({stateChanger, ...rest}) => {
return(
<button onClick={() => stateChanger('New data')}></button>
)
}
To update the parent state from the children component, either we can use additional dependencies like Redux or we can use this simple method of passing the state of the parent to the children and handling it accordingly. In this example, we will build a React application which takes the state and the method to update it from the parent component and pass it to the children component and after handling it we will pass the updated state to the parent component. In this article, we are going to see how to update the parent state from a child component in a React application.
App.jsx
import React, { useLayoutEffect, useState } from 'react';
const App = () => {
const [name, setName] = useState('Rahul');
return (
<div>
{name} has email id of rahul@tutorialspoint.com
<div>
<Child name={name} change={setName} />
</div>
</div>
);
};
const Child = ({ name, change }) => {
const [newName, setNewName] = useState(name);
return (
<div>
<input
placeholder="Enter new name"
value={newName}
onChange={(e) => setNewName(e.target.value)}
/>
<button onClick={() => change(newName )}>Change</button>
</div>
);
};
export default App;Step 1: Create a React application using the following command: Step to Run Application: Run the application using the following command from the root directory of the project: Step 2: After creating your project folder i.e. foldername, move to it using the following command: Creating React Application:
Creating React Application:
npx create - react - app foldername
cd foldername
Project Structure: It will look like the following.
Filename: App.js
import React, { Component } from "react";
class App extends Component {
state = {
text: 'click me'
}
// Function to update state
handleUpdate = (newtext) => {
this.setState({ text: newtext })
}
render() {
return (
<div>
<Child
text={this.state.text}
// Passing a function to child
updateState={this.handleUpdate}>
</Child>
</div>
);
}
}
class Child extends Component {
render() {
return (
<button
// Using parent props to update parent state
onClick={() => this.props
.updateState('parent state changed')}>
{this.props.text}
</button>
)
}
}
export default App;
Define a function that handles the click and calls the function passed as props from the parent component Declare a state and a setter for the title or slug Pass that function down as props to the child component Define a function to update the state
Parent component
const [currentPage, setCurrentPage] = useState('');
const updatePage = title => {
setCurrentPage(title)
}
return (<div>
//... some parent component code
<ChildComponent updatePage={updatePage} />
</div>)
Child Component
export const ChildComponent = ({updatePage}) => {
const title = 'Current Article Title';
const handleClick = () => {
updatePage(title)
}
return (<div>
//... some child component code
<button onClick={handleClick} >{title}</button>
</div>)
}
We hope this article will help you to understand how to change parent component state using hooks in ReactJs. If you like this article then please follow us on Facebook and Twitter. Child component holds the Input field and we are going to send the input field value to the Parent component. So let’s create the Parent component first. As you see that we set the onChange property to the Child component. Next step is to create the Child component.
function Parent() {
const [value, setValue] = React.useState("");
function handleChange(newValue) {
setValue(newValue);
}
// We pass a callback to Child
return <Child value={value} onChange={handleChange} />;
}function Child(props) {
function handleChange(event) {
// Here, we invoke the callback with the new value
props.onChange(event.target.value);
}
return <input value={props.value} onChange={handleChange} />
}Hi, You could try the following:
function Parent() {
const [value, setValue] = React.useState("");
// Detect the value change from child
React.useEffect(() => {
// Apply the login based on value change
}, [value]);
function handleChange(newValue) {
setValue(newValue);
}
...
...
}Don't pass updateState down to the child component. What you should do instead is give the child component an onClick prop. Then the parent component can pass a function that will call updateState itself. That will keep all of Parent's state updates contained within Parent and also make the child component more reusable. The other answers are right. Btw you can just pass setState down directly, you don't need to wrap it in updateState. Another way to do it : onClick = {updateState.bind(null,"test")}, this way you are not creating many different handlers but just one.
Hi guys. I'm developing an app where a children component can change a useState of his parent. I'm currently doing it like this:
This is the parent:
const Parent = () => {
const [state, setState] = useState('');
const updateState = (newState) => {
setState(newState)
}
return (
<Children updateState={updateState} />
)
}
This is the children:
const Children = ({updateState}) => {
return (
<button onClick={updateState('test')}>Test</button>
)
}
To lift state up, you must locate the closest common parent component of both of the child components that you want to coordinate: Sometimes, you want the state of two components to always change together. To do it, remove state from both of them, move it to their closest common parent, and then pass it down to them via props. This is known as lifting state up, and it’s one of the most common things you will do writing React code. You will give control of the Panel’s isActive to its parent component. This means that the parent component will pass isActive to Panel as a prop instead. Start by removing this line from the Panel component:
import { useState } from 'react';
function Panel({ title, children }) {
const [isActive, setIsActive] = useState(false);
return (
<section className="panel">
<h3>{title}</h3>
{isActive ? (
<p>{children}</p>
) : (
<button onClick={() => setIsActive(true)}>
Show
</button>
)}
</section>
);
}
export default function Accordion() {
return (
<>
<h2>Almaty, Kazakhstan</h2>
<Panel title="About">
With a population of about 2 million, Almaty is Kazakhstan's largest city. From 1929 to 1997, it was its capital city.
</Panel>
<Panel title="Etymology">
The name comes from <span lang="kk-KZ">алма</span>, the Kazakh word for "apple" and is often translated as "full of apples". In fact, the region surrounding Almaty is thought to be the ancestral home of the apple, and the wild <i lang="la">Malus sieversii</i> is considered a likely candidate for the ancestor of the modern domestic apple.
</Panel>
</>
);
}
const [isActive, setIsActive] = useState(false);function Panel({
title,
children,
isActive
}) {const [activeIndex, setActiveIndex] = useState(0);<> <Panel isActive={activeIndex === 0} onShow={() => setActiveIndex(0)} > ... </Panel> <Panel isActive={activeIndex === 1} onShow={() => setActiveIndex(1)} > ... </Panel></>