Develop Reference

Manually Focusing a DraftJS Component Only Works the First Time

I have rendered a a React Draft WYSIWYG component using the following code:
InputTextArea.js (parent component in charge of managing focus()
import { useRef } from "react"
import EditorConvertToHTML from "./EditorConvertToHTML";
export default function InputTextArea({ editing }) { // this prop is a state variable passed from parent (setter function not needed here so not passed)
const editorRef = useRef()
useEffect(() => { // if user clicks a button which sets 'editing' to true, set focus to the rich text editor component
if(editing) {
editorRef.current.focus()
}
}, [editing])
return(
<EditorConvertToHTML
innerRef={editorRef}
readOnly={!editing}
/>
)
}
EditorConvertToHTML (actual rich text editor component
import { Component } from 'react';
import { EditorState } from 'draft-js';
import { Editor } from 'react-draft-wysiwyg';
export default class EditorConvertToHTML extends Component {
state = {
editorState: EditorState.createEmpty()
}
onEditorStateChange = (editorState) => {
this.setState({
editorState,
});
};
render() {
const { editorState } = this.state;
return (
<Editor
editorRef={(ref) => this.props.innerRef.current = ref}
editorState={editorState}
onEditorStateChange={this.onEditorStateChange}
readOnly={this.props.readOnly}
/>
);
}
}
The first time that editing is set to true, ReactJS successfully focuses EditorConvertToHTML component. However, when I set it to false and then again to true, the component no longer becomes focused.
I know that the useEffect and contained if(editing) conditions are triggered each time that editing is set to true because I have added a logger in there which confirmed it's being called. I get no errors in console.
Why is focus working only the first time that editing is set to true?
If there's any other information that you'd find helpful, please let me know.
Edit:
I logged the editorRef object into the console just before the focus() method gets called and see that the object of the variable is different between the first time (when focus() works) and second time (when focus() doesn't work), where first time it's a DraftEditor object, and second time it's a different object.
Why is the object in editorRef changing and is there a way I can ensure that focus() works every time that editing is set to true?

Forcefully update the component on updated value inside the render method react native

I am trying to forcefully rerender the complete component on value change inside the render function.
Below is a sample code to explain my problem. Profile component I am calling after the login and it's called and two functions inside this getting called and the value is set in the state. Now I am on another screen where I am updating mssidnNumber inside the context and that change I can see in the Profile render() function val. let val = this.context.mssidnNumber; and this val value will change on condition so on this basis I am trying to rerender the complete Profile component again so all values will update. How can I do this please help? Is that possible?
import React, { Component } from 'react';
import { View} from 'react-native';
class Profile extends Component {
constructor(props) {
super(props);
}
async componentDidMount() {
this.Profilefunction();
}
Profilefunction = () =>{
this.setState({})
await this.profile2fucntion();
}
profile2fucntion =() => {
}
render() {
let val = this.context.mssidnNumber;
return (
<View>
</View>
);
}
}
export default Profile;

How to pass a value from a function to a class in React?

Goal
I am aiming to get the transcript value, from the function Dictaphone and pass it into to the SearchBar class, and finally set the state term to transcript.
Current code
import React from 'react';
import SpeechRecognition, { useSpeechRecognition } from 'react-speech-recognition';
const Dictaphone = () => {
const { transcript } = useSpeechRecognition()
if (!SpeechRecognition.browserSupportsSpeechRecognition()) {
return null
}
return (
<div>
<button onClick={SpeechRecognition.startListening}>Start</button>
<p>{transcript}</p>
</div>
)
}
class SearchBar extends React.Component {
constructor(props) {
super(props);
this.state = {
term: ''
}
this.handleTermChange = this.handleTermChange.bind(this);
}
handleTermChange(event) {
this.setState({ term: event.target.value });
}
render() {
return (
<div className="SearchBar">
<input onChange={this.handleTermChange} placeholder="Enter some text..." />
<Dictaphone />
</div>
)
}
}
export { SearchBar };
Problem
I can render the component <Dictaphone /> within my SearchBar. The only use of that is it renders a button and the transcript. But that's not use for me.
What I need to do is, get the Transcript value and set it to this.state.term so my input field within my SearchBar changes.
What I have tried
I tried creating an object within my SearchBar component and called it handleSpeech..
class SearchBar extends React.Component {
constructor(props) {
super(props);
this.state = {
term: ''
}
this.handleTermChange = this.handleTermChange.bind(this);
}
handleTermChange(event) {
this.setState({ term: event.target.value });
}
handleSpeech() {
const { transcript } = useSpeechRecognition()
if (!SpeechRecognition.browserSupportsSpeechRecognition()) {
return null
}
SpeechRecognition.startListening();
this.setState({ term: transcript});
}
render() {
return (
<div className="SearchBar">
<input onChange={this.handleTermChange} placeholder="Enter some text..." />
<button onClick={this.handleSpeech}>Start</button>
</div>
)
}
}
Error
But I get this error:
React Hook "useSpeechRecognition" cannot be called in a class component. React Hooks must be called in a React function component or a custom React Hook function react-hooks/rules-of-hooks
React Hooks must be called in a React function component or a custom React Hook function

Well, the error is pretty clear. You're trying to use a hook in a class component, and you can't do that.
Option 1 - Change SearchBar to a Function Component
If this is feasible, it would be my suggested solution as the library you're using appears to be built with that in mind.
Option 2
Communicate between Class Component <=> Function Component.
I'm basing this off your "current code".
import React, { useEffect } from 'react';
import SpeechRecognition, { useSpeechRecognition } from 'react-speech-recognition';
const Dictaphone = ({ onTranscriptChange }) => {
const { transcript } = useSpeechRecognition();
// When `transcript` changes, invoke a function that will act as a callback to the parent (SearchBar)
// Note of caution: this code may not work perfectly as-is. Invoking `onTranscriptChange` would cause the parent's state to change and therefore Dictaphone would re-render, potentially causing infinite re-renders. You'll need to understand the hook's behavior to mitigate appropriately.
useEffect(() => {
onTranscriptChange(transcript);
}, [transcript]);
if (!SpeechRecognition.browserSupportsSpeechRecognition()) {
return null
}
return (
<div>
<button onClick={SpeechRecognition.startListening}>Start</button>
<p>{transcript}</p>
</div>
)
}
class SearchBar extends React.Component {
constructor(props) {
super(props);
this.state = {
transcript: ''
}
this.onTranscriptChange = this.onTranscriptChange.bind(this);
}
onTranscriptChange(transcript){
this.setState({ transcript });
}
render() {
return (
<div className="SearchBar">
<input onChange={this.handleTermChange} placeholder="Enter some text..." />
<Dictaphone onTranscriptChange={onTranscriptChange} />
</div>
)
}
}

useSpeechRecognition is a React hook, which is a special type of function that only works in specific situations. You can't use hooks inside a class-based component; they only work in function-based components, or in custom hooks. See the rules of hooks for all the limitations.
Since this hook is provided by a 3rd party library, you have a couple of options. One is to rewrite your search bar component to be a function. This may take some time if you're unfamiliar with hooks.
You can also see if the react-speech-recognition library provides any utilities that are intended to work with class-based components.

Uncaught RangeError Maximum call stack size exceeded in React App

I'm learning React and for training, I want to create a basic Todo app. For the first step, I want to create a component called AddTodo that renders an input field and a button and every time I enter something in the input field and press the button, I want to pass the value of the input field to another component called TodoList and append it to the list.
The problem is when I launch the app, the AddTodo component renders successfully but when I enter something and press the button, the app stops responding for 2 seconds and after that, I get this: Uncaught RangeError: Maximum call stack size exceeded and nothing happens.
My app source code: Main.jsx
import React, {Component} from 'react';
import TodoList from 'TodoList';
import AddTodo from 'AddTodo';
class Main extends Component {
constructor(props) {
super(props);
this.setNewTodo = this.setNewTodo.bind(this);
this.state = {
newTodo: ''
};
}
setNewTodo(todo) {
this.setState({
newTodo: todo
});
}
render() {
var {newTodo} = this.state;
return (
<div>
<TodoList addToList={newTodo} />
<AddTodo setTodo={this.setNewTodo}/>
</div>
);
}
}
export default Main;
AddTodo.jsx
import React, {Component} from 'react';
class AddTodo extends Component {
constructor(props) {
super(props);
this.handleNewTodo = this.handleNewTodo.bind(this);
}
handleNewTodo() {
var todo = this.refs.todo.value;
this.refs.todo.value = '';
if (todo) {
this.props.setTodo(todo);
}
}
render() {
return (
<div>
<input type="text" ref="todo" />
<button onClick={this.handleNewTodo}>Add to Todo List</button>
</div>
);
}
}
AddTodo.propTypes = {
setTodo: React.PropTypes.func.isRequired
};
export default AddTodo;
TodoList.jsx
import React, {Component} from 'react';
class TodoList extends Component {
constructor(props) {
super(props);
this.renderItems = this.renderItems.bind(this);
this.state = {
todos: []
};
}
componentDidUpdate() {
var newTodo = this.props.addToList;
var todos = this.state.todos;
todos = todos.concat(newTodo);
this.setState({
todos: todos
});
}
renderItems() {
var todos = this.state.todos;
todos.map((item) => {
<h4>{item}</h4>
});
}
render() {
return (
<div>
{this.renderItems()}
</div>
);
}
}
export default TodoList;

First time componentDidUpdate is called (which happens after first change in its props/state, which in your case happens after adding first todo) it adds this.props.addToList to this.state.todo and updates state. Updating state will run componentDidUpdate again and it adds the value of this.props.addToList to 'this.state.todo` again and it goes infinitely.
You can fix it with some dirty hacks but your approach is a bad approach overall. Right thing to do is to keep todos in parent component (Main), append the new todo to it in setNewTodo (you may probably rename it to addTodo) and pass the todos list from Main state to TodoList: <TodoList todos={this.state.todos}/> for example.

The basic idea of react is whenever you call setState function, react component get updated which causes the function componentDidUpdate to be called again when the component is updated.
Now problem here is you are calling setState function inside componentDidUpdate which causes the component to update again and this chain goes on forever. And every time componentDidUpdate is called it concat a value to the todo. So a time come when the memory gets full and it throws an error. You should not call setState function inside functions like componentWillUpdate,componentDidUpdate etc.
One solution can be to use componentWillReceiveProps instead of componentDidUpdate function like this:
componentDidUpdate(nextProps) {
var newTodo = nextProps.addToList;
this.setState(prevState => ({
todos: prevState.todos.concat(newTodo)
}));
}

React: componentDidMount + setState not re-rendering the component

I'm fairly new to react and struggle to update a custom component using componentDidMount and setState, which seems to be the recommended way of doing it. Below an example (includes an axios API call to get the data):
import React from 'react';
import {MyComponent} from 'my_component';
import axios from 'axios';
export default class Example extends React.Component {
constructor(props) {
super(props);
this.state = {
data: []
};
}
GetData() {
return axios.get('http://localhost:5000/<route>');
}
componentDidMount() {
this.GetData().then(
(resp) => {
this.setState(
{data: resp.data}
)
}
)
}
render() {
return (
<MyComponent data={this.state.data} />
);
}
}
Doing console.log(this.state.data) just below render() shows that this.state.data does indeed get updated (from [] to whatever the API returns). However, the problem appears to be that MyComponent isn't rendered afresh by componentDidMount. From the Facebook react docs:
Setting state in this method will trigger a re-rendering.
This does not seem to be the case here: The constructor of MyComponent only gets called once (where this.props.data = []) and the component does not get rendered again. I'd be great if someone could explain why this is and whether there's a solution or a different way altogether to get the updating done.
UPDATE
I've added the code for MyComponent (minus some irrelevant features, as indicated by ...). console.log(data_array) prints an empty array.
import React from 'react';
class DataWrapper {
constructor(data) {
this._data = data;
}
getSize() {
return this._data.length;
}
...
}
export class MyComponent extends React.Component {
constructor(props) {
super(props);
this._dataWrapper = new DataWrapper(this.props.data);
this.state = {
data_array: this._dataWrapper,
};
}
render() {
var {data_array} = this.state;
console.log(data_array);
return (
...
);
}
}

You are falling victim to this antipattern.
In MyComponent constructor, which only gets called the first time it mounts, passed your empty array through new DataWrapper and now you have some local state which will never be updated no matter what your parent does.
It's always better to have one source of truth, just one state object anywhere (especially for things like ajax responses), and pass those around via props. In fact this way, you can even write MyComponent as a simple function, instead of a class.
class Example extends Component {
state = { data: [] }
GetData() { .. }
componentDidMount() {
this.GetData().then(res =>
this.setState({data: new DataWrapper(res.data)})
)
}
render() { return <MyComponent data={this.state.data} /> }
}
...
function MyComponent (props) {
// props.data will update when your parent calls setState
// you can also call DataWrapper here if you need MyComponent specific wrapper
return (
<div>..</div>
)
}

In other words what azium is saying, is that you need to turn your receiving component into a controlled one. Meaning, it shouldn't have state at all. Use the props directly.
Yes, even turn it into a functional component. This helps you maintain in your mind that functional components generally don't have state (it's possible to put state in them but ... seperation of concerns).
If you need to edit state from that controlled component, provide the functions through props and define the functions in the "master" component. So the master component simply lends control to the children. They want anything they talk to the parent.
I'm not posting code here since the ammendment you need to make is negligible. Where you have this.state in the controlled component, change to this.props.