How to do React forceUpdate() to a child component?
If child component is not memoized then rendering its parent will render the child.
If child component is memoized, you could force update with its reference.
And of course, passing different properties to a child, changing its state, will re-render it.
Changing the key will UNMOUNT the component, it is like making a conditional rendering on it.
Here is an example demonstating everything mentioned:
class Child extends React.Component {
componentDidMount() {
console.log("mounted");
}
render() {
console.log("rendered");
return <div>Child</div>;
}
}
class App extends React.Component {
state = {
counter: 0
};
childRef = React.createRef();
onClick = () => this.forceUpdate();
onCounter = () => this.setState({ counter: this.state.counter + 1 });
onRef = () => this.childRef.current.forceUpdate();
render() {
return (
<>
<Child key={this.state.counter} ref={this.childRef} />
<button onClick={this.onClick}>Render</button>
<button onClick={this.onCounter}>Update Key</button>
<button onClick={this.onRef}>Render with ref</button>
</>
);
}
}
How to force update child component from parent component in reactjs
child always re-renders when parent does..
use this code for your project
Parent.js
import React, { Component } from "react";
import Child from './child'
class Parent extends Component {
constructor(props) {
super(props);
this.state ={
lblName: "Name",
lblGender: "Gender",
lblDOB: "Date Of Birth",
lblNatio: "Nationality",
};
}
ChangeLanguage(lang, e){
if(lang === "en"){
this.setState(
{
lblName: "Name",
lblGender: "Gender",
lblDOB: "Date Of Birth",
lblNatio: "Nationality",
});
}
else if(lang === "sp"){
this.setState(
{
lblName: "Nombre",
lblGender: "Género",
lblDOB: "Fecha de nacimiento",
lblNation: "Nacionalidad",
});
}
}
render() {
return (
<div>
<Child {...this.state} />
<button onClick = {this.ChangeLanguage.bind(this, "en")}>English</button>
<button onClick = {this.ChangeLanguage.bind(this, "sp")}>Spanish</button>
</div>
)}
}
export default Parent
Child.js
import React, { Component } from "react";
class Child extends Component {
constructor(props) {
super(props);
}
render() {
return (
<div>
<div>
<label>{this.props.lblName}</label>
<input type="Text"></input>
</div>
<div>
<label>{this.props.lblGender}</label>
<input type="Text"></input>
</div>
<div>
<label>{this.props.lblDOB}</label>
<input type="Date"></input>
</div>
<div>
<label>{this.props.lblNation}</label>
<input type="Text"></input>
</div>
</div>
)}
}
export default Child
Sample index.js file
import React, {Component} from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import Parent from './parent'
class App extends Component {
render() {
return (
<div className="App">
<Parent />
</div>
);
}
}
ReactDOM.render(<App />, document.getElementById('root'))
for now all the files are in the src folder
How do I force parent component re render from child component
This is an example of what a Context that wrapped a Playlist object could look like.
Here we have 2 components, PlaylistDetails
and AddSongForm
, and a single Context, PlaylistContext
. Our PlaylistProvider
wraps the PlaylistContext
and exposes both the playlist state (the list of songs) and a function to update that state. The PlaylistDetails
and AddSongForm
components read the playlist
state from the PlaylistProvider
so whenever that is updated they re-render automatically.
import { createContext, useContext, useState } from "react";
const PlaylistContext = createContext(null);
const PlaylistProvider = ({ children }) => {
const [playlist, setPlaylist] = useState([]);
const updatePlaylist = (songName) => {
setPlaylist((prevPlaylist) => [...prevPlaylist, songName]);
};
return (
<PlaylistContext.Provider value={{ playlist, updatePlaylist }}>
{children}
</PlaylistContext.Provider>
);
};
const PlaylistDetails = () => {
const { playlist } = useContext(PlaylistContext);
if (playlist.length === 0) {
return null;
}
return (
<>
<h1>Songs:</h1>
<ul>
{playlist.map((song) => (
<li key={song}>{song}</li>
))}
</ul>
</>
);
};
const AddSongForm = () => {
const { updatePlaylist } = useContext(PlaylistContext);
const [songName, setSongName] = useState(null);
return (
<form
onSubmit={(e) => {
updatePlaylist(songName);
e.preventDefault();
}}
>
<label>
Song Name:
<input type="text" onChange={(e) => setSongName(e.target.value)} />
</label>
<button type="submit">Add Song</button>
</form>
);
};
export default function App() {
return (
<PlaylistProvider>
<PlaylistDetails />
<AddSongForm />
</PlaylistProvider>
);
}
How can i refresh my child componet by using a button click on parent componet?
Changing state should re-render the current component and all the child components inside it.
I ran your code and there is a mistake with how you defined the setState method. You need to use arrow function, otherwise this
will be undefined.
So change your submit button like following and it should work.
submit = () => {
this.setState({ isRefreshClicked: true });
};
Here's the stackblitz: https://stackblitz.com/edit/react-f5q3n8?file=src/MyComponent.js
How to re-render parent component from child component
You have to have state
in the parent component and pass down this state to the child component:
import React, { Component } from "react";
import Child from "./Child";
class Parent extends Component {
constructor(props) {
super(props);
this.state = {
counter: 0
};
}
rerender = () => {
this.forceUpdate();
};
forceUpdate = () => {
this.setState((state) => ({
counter: state.counter + 1
}));
};
render() {
console.log("got rendered");
return (
<div>
<p className="animate-left" key={this.state.counter}>Animation</p>
<Child rerender={this.rerender} />
</div>
);
}
}
export default Parent;
React JS: State Changes on Child component updating the Parent Component
From gif it seems to me like whole page is reloading, but I'm not sure what is inside MediumButton component. By default button inside form element will submit the form on click, you need to implement preventDefault in your button onClick handler, here is an example how to do it:
function App() {
const handleClick = (e) => {
e.preventDefault();
}
return (
<div className="App">
<form>
<p>This is simple form</p>
<button onClick={(e) => handleClick(e)}>hello</button>
</form>
</div>
)
};
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