Develop Reference

React child callback not being executed after being passed down twice

I am working on the following project https://github.com/codyc4321/react-udemy-course section 11 the videos app. The udemy course is found at https://www.udemy.com/course/react-redux/learn/lecture/12531374#overview.
The instructor is passing a callback down to multiple children and calling it in the lowest videoItem and the code is supposed to console log something out. I have no console log in my browser even though I've copied the code as written and double checked for spelling errors.
At the main level is App.js:
import React from 'react';
import youtube from '../apis/youtube';
import SearchBar from './SearchBar';
import VideoList from './VideoList';
class App extends React.Component {
state = {videos: [], selectedVideo: null};
onTermSubmit = async term => {
const response = await youtube.get('/search', {
params: {
q: term
}
});
// console.log(response.data.items);
this.setState({videos: response.data.items});
};
onVideoSelect = video => {
console.log('from the app', video);
}
render() {
return (
<div className="ui container">
<SearchBar onFormSubmit={this.onTermSubmit} />
<VideoList
onVideoSelect={this.onVideoSelect}
videos={this.state.videos} />
</div>
)
}
}
export default App;
videoList.js
import React from 'react';
import VideoItem from './VideoItem';
const VideoList = ({videos, onVideoSelect}) => {
const rendered_list = videos.map(video => {
return <VideoItem onVideoSelect={onVideoSelect} video={video} />
});
return <div className="ui relaxed divided list">{rendered_list}</div>;
};
export default VideoList;
the videoItem.js
import React from 'react';
import './VideoItem.css';
const VideoItem = ({video, onVideoSelect}) => {
return (
<div onClick={() => onVideoSelect(video)} className="item video-item">
<img
src={video.snippet.thumbnails.medium.url}
className="ui image"
/>
<div className="content">
<div className="header">{video.snippet.title}</div>
</div>
</div>
);
}
export default VideoItem;
The code that isn't running is
onVideoSelect = video => {
console.log('from the app', video);
}

My guess is that it has something to do with a key prop not being present in the map - I'm not super well versed with class components but I can't find anything else funky so maybe try adding a unique key prop in the map.
When rendering components through a map react needs help with assigning unique identifiers to keep track of re-renders etc for performance, that also applies to knowing which specific instance called a class method.
If you don't have a unique ID in the video prop you can use an index in a pinch, although ill advised, it can be found as the second parameter in the map function. The reason it's ill advised to use an index is if there are multiple children with the same index in the same rendering context, obviously the key parameter could be confused.
Okay-ish:
const rendered_list = videos.map((video, index) => {
return <VideoItem key={index} onVideoSelect={onVideoSelect} video={video} />});
Better:
const rendered_list = videos.map((video, index) => {
return <VideoItem key={video.id} onVideoSelect={onVideoSelect} video={video} />});

React: Persisting State Using Local Storage

I am coding an app in which there is a collection of reviews and a person can respond to a review, but each review can only have one response. So far, I am doing this by rendering a ReviewResponseBox component in my ReviewCardDetails component and passing the review_id as props.
I have implemented the logic so that once there is one ReviewResponse, the form to write another will no longer appear. However, before I was initializing the state in this component with an empty array, so when I refreshed my page the response went away and the form came back up. (This is now commented out)
I am trying to resolve this by persisting my state using React LocalStorage but am having trouble writing my method to do this. Here is what I have so far:
Component that renders ReviewResponseBox and passes review_id as props:
import React from "react";
import './Review.css';
import { useLocation } from "react-router-dom";
import StarRatings from "react-star-ratings";
import ReviewResponseBox from "../ReviewResponse/ReviewResponseBox";
const ReviewCardDetails = () => {
const location = useLocation();
const { review } = location?.state; // ? - optional chaining
console.log("history location details: ", location);
return (
<div key={review.id} className="card-deck">
<div className="card">
<div>
<div className='card-container'>
<h4 className="card-title">{review.place}</h4>
<StarRatings
rating={review.rating}
starRatedColor="gold"
starDimension="20px"
/>
<div className="card-body">{review.content}</div>
<div className="card-footer">
{review.author} - {review.published_at}
</div>
</div>
</div>
</div>
<br></br>
<ReviewResponseBox review_id={review.id}/>
</div>
);
};
export default ReviewCardDetails;
component that I want to keep track of the state so that it can render the form or response:
import React from 'react';
import ReviewResponse from './ReviewResponse';
import ReviewResponseForm from './ReviewResponseForm';
import { reactLocalStorage } from "reactjs-localstorage";
class ReviewResponseBox extends React.Component {
// constructor() {
// super()
// this.state = {
// reviewResponses: []
// };
// }
fetchResponses = () => {
let reviewResponses = [];
localStorage.setResponses
reviewResponses.push(reviewResponse);
}
render () {
const reviewResponses = this.getResponses();
const reviewResponseNodes = <div className="reviewResponse-list">{reviewResponses}</div>;
return(
<div className="reviewResponse-box">
{reviewResponses.length
? (
<>
{reviewResponseNodes}
</>
)
: (
<ReviewResponseForm addResponse={this.addResponse.bind(this)}/>
)}
</div>
);
}
addResponse(review_id, author, body) {
const reviewResponse = {
review_id,
author,
body
};
this.setState({ reviewResponses: this.state.reviewResponses.concat([reviewResponse]) }); // *new array references help React stay fast, so concat works better than push here.
}
getResponses() {
return this.state.reviewResponses.map((reviewResponse) => {
return (
<ReviewResponse
author={reviewResponse.author}
body={reviewResponse.body}
review_id={this.state.review_id} />
);
});
}
}
export default ReviewResponseBox;
Any guidance would be appreciated

You would persist the responses to localStorage when they are updated in state using the componentDidUpdate lifecycle method. Use the componentDidMount lifecycle method to read in the localStorage value and set the local component state, or since reading from localStorage is synchronous directly set the initial state.
I don't think you need a separate package to handle this either, you can use the localStorage API easily.
import React from "react";
import ReviewResponse from "./ReviewResponse";
import ReviewResponseForm from "./ReviewResponseForm";
class ReviewResponseBox extends React.Component {
state = {
reviewResponses: JSON.parse(localStorage.getItem(`reviewResponses-${this.props.review_id}`)) || []
};
storageKey = () => `reviewResponses-${this.props.review_id}`;
componentDidUpdate(prevProps, prevState) {
if (prevState.reviewResponses !== this.state.reviewResponses) {
localStorage.setItem(
`reviewResponses-${this.props.review_id}`,
JSON.stringify(this.state.reviewResponses)
);
}
}
render() {
const reviewResponses = this.getResponses();
const reviewResponseNodes = (
<div className="reviewResponse-list">{reviewResponses}</div>
);
return (
<div className="reviewResponse-box">
{reviewResponses.length ? (
<>{reviewResponseNodes}</>
) : (
<ReviewResponseForm addResponse={this.addResponse.bind(this)} />
)}
</div>
);
}
addResponse(review_id, author, body) {
const reviewResponse = {
review_id,
author,
body
};
this.setState({
reviewResponses: this.state.reviewResponses.concat([reviewResponse])
}); // *new array references help React stay fast, so concat works better than push here.
}
getResponses() {
return this.state.reviewResponses.map((reviewResponse) => {
return (
<ReviewResponse
author={reviewResponse.author}
body={reviewResponse.body}
review_id={this.state.review_id}
/>
);
});
}
}

How to use forEach in react js

I want to create a function which iterate over all element with same class and remove a specific class.
It could be done easily using JavaScript.
const boxes = document.querySelectorAll(".box1");
function remove_all_active_list() {
boxes.forEach((element) => element.classList.remove('active'));
}
But how can I do this similar thing is ReactJs. The problem which I am facing is that I can't use document.querySelectorAll(".box1") in React but, I can use React.createRef() but it is not giving me all elements, it's only giving me the last element.
This is my React Code
App.js
import React, { Component } from 'react';
import List from './List';
export class App extends Component {
componentDidMount() {
window.addEventListener('keydown', this.keypressed);
}
keypressed = (e) => {
if (e.keyCode == '38' || e.keyCode == '40') this.remove_all_active_list();
};
remove_all_active_list = () => {
// boxes.forEach((element) => element.classList.remove('active'));
};
divElement = (el) => {
console.log(el);
el.forEach((element) => element.classList.add('active'))
};
render() {
return (
<div className="container0">
<List divElement={this.divElement} />
</div>
);
}
}
export default App;
List.js
import React, { Component } from 'react';
import data from './content/data';
export class List extends Component {
divRef = React.createRef();
componentDidMount() {
this.props.divElement(this.divRef)
}
render() {
let listItem = data.map(({ title, src }, i) => {
return (
<div className="box1" id={i} ref={this.divRef} key={src}>
<img src={src} title={title} align="center" alt={title} />
<span>{title}</span>
</div>
);
});
return <div className="container1">{listItem}</div>;
}
}
export default List;
Please tell me how can I over come this problem.

The short answer
You wouldn't.
Instead you would conditionally add and remove the class to the element, the component, or to the collection.map() inside your React component.
Example
Here's an example that illustrates both:
import styles from './Example.module.css';
const Example = () => {
const myCondition = true;
const myCollection = [1, 2, 3];
return (
<div>
<div className={myCondition ? 'someGlobalClassName' : undefined}>Single element</div>
{myCollection.map((member) => (
<div key={member} className={myCondition ? styles.variant1 : styles.variant2}>
{member}
</div>
))}
</div>
);
};
export default Example;
So in your case:
You could pass active prop to the <ListItem /> component and use props.active as the condition.
Alternatively you could send activeIndex to <List /> component and use index === activeIndex as the condition in your map.
Explanation
Instead of adding or removing classes to a HTMLElement react takes care of rendering and updating the whole element and all its properties (including class - which in react you would write as className).
Without going into shadow dom and why react may be preferable, I'll just try to explain the shift in mindset:
Components do not only describe html elements, but may also contain logic and behaviour. Every time any property changes, at the very least the render method is called again, and the element is replaced by the new element (i.e. before without any class but now with a class).
Now it is much easier to change classes around. All you need to do is change a property or modify the result of a condition (if statement).
So instead of selecting some elements in the dom and applying some logic them, you would not select any element at all; the logic is written right inside the react component, close to the part that does the actual rendering.
Further reading
https://reactjs.org/docs/state-and-lifecycle.html
Please don't hessitate to add a comment if something should be rephrased or added.

pass the ref to the parent div in List component.
...
componentDidMount() {
this.props.divElement(this.divRef.current)
}
...
<div ref={this.divRef} className="container1">{listItem}</div>
then in App
divElement = (el) => {
console.log(el);
el.childNodes.forEach((element) => element.classList.add('active'))
}
hope this will work. here is a simple example
https://codesandbox.io/s/staging-microservice-0574t?file=/src/App.js

App.js
import React, { Component } from "react";
import List from "./List";
import "./styles.css";
export class App extends Component {
state = { element: [] };
ref = React.createRef();
componentDidMount() {
const {
current: { divRef = [] }
} = this.ref;
divRef.forEach((ele) => ele?.classList?.add("active"));
console.log(divRef);
window.addEventListener("keydown", this.keypressed);
}
keypressed = (e) => {
if (e.keyCode == "38" || e.keyCode == "40") this.remove_all_active_list();
};
remove_all_active_list = () => {
const {
current: { divRef = [] }
} = this.ref;
divRef.forEach((ele) => ele?.classList?.remove("active"));
// boxes.forEach((element) => element.classList.remove('active'));
console.log(divRef);
};
render() {
return (
<div className="container0">
<List divElement={this.divElement} ref={this.ref} />
</div>
);
}
}
export default App;
List.js
import React, { Component } from "react";
import data from "./data";
export class List extends Component {
// divRef = React.createRef();
divRef = [];
render() {
let listItem = data.map(({ title, src }, i) => {
return (
<div
className="box1"
key={i}
id={i}
ref={(element) => (this.divRef[i] = element)}
>
<img src={src} title={title} align="center" alt={title} width={100} />
<span>{title}</span>
</div>
);
});
return <div className="container1">{listItem}</div>;
}
}
export default List;
Create ref for List component and access their child elements. When key pressed(up/down arrow) the elements which has classname as 'active' will get removed. reference

React / Functional component / Conditional render on callback / Not Working

Why this does not work ?
import React from 'react';
function Room() {
let check = null;
const ibegyouwork = () => {
check = <button>New button</button>;
}
return (
<div>
<button onClick={ibegyouwork}>Display my button now !!!!</button>
{check}
</div>
);
}
export default Room;
And this works fine ?
import React from 'react';
function Room() {
let check = null;
return (
<div>
<button>No need for this button because in this case the second button is auto-displayed</button>
{check}
</div>
);
}
export default Room;
Basically I try to render a component based on a condition. This is a very basic example. But what I have is very similar. If you wonder why I need to update the check variable inside that function is because in my example I have a callback function there where I receive an ID which I need to use in that new component.
The example that I provided to you is basically a button and I want to show another one when I press on this one.
I am new to React and despite I searched in the past 2 hours for a solution I couldn't find anything to address this issue.
Any tips are highly appreciated !

Your component has no idea that something has changed when you click the button. You will need to use state in order to inform React that a rerender is required:
import React, {useState} from 'react'
function Room() {
const [check, setCheck] = useState(null);
const ibegyouwork = () => {
setCheck(<button>New button</button>);
}
return (
<div>
<button onClick={ibegyouwork}>Display my button now !!!!</button>
{check}
</div>
);
}
export default Room;
When you call setCheck, React basically decides that a rerender is required, and updates the view.

The latter is working because there are no changes to the check value that should appear on the DOM.
If check changes should impact and trigger the React render function, you would want to use a state for show/hide condition.
import React from 'react';
const Check = () => <button>New button</button>;
function Room() {
const [show, setShow] = React.useState(false);
const ibegyouwork = () => {
setShow(true);
}
return (
<div>
<button onClick={ibegyouwork}>Display my button now !!!!</button>
{show && <Check />}
</div>
);
}
export default Room;

react-select can load async data

I'm trying to build a select component using react-select plugin.
In the process of implementing this project, I have some kind of tricky problem with that. Check out my source code here: https://codesandbox.io/s/j148r99695
The problem that I have is I want to fetch all genresList data from the server and mapping them to select component. But somehow or I do wrong something, It's not working. Please see source code above to help me.
I fetch data from Movies component. Its work well and I pass a props to FormFilter component: <FormFilter genresList={this.state.genres} />. And in the FormFilter component, I check this.props.genresList, it's available. But when I'm trying to assign it to FormFilter state and console.log("state", this.state.genres); that. It's empty. Anyone can tell me why?
Default react-select using value and label to display data to select component. But you know some cases we have to custom that. I try it out by using map to transform to other arrays. But It's the best way? How can I custom valueKey and labelKey.
I'm using react-select beta version2.
UPDATE: I was fixed my project. Please check out the link below. Somehow it's not working. I was commend inside source code.
https://codesandbox.io/s/moym59w39p

So to make it works I have changed the FormFilter.js implementation:
import React, { Component } from "react";
import * as Animated from "react-select/lib/animated";
import AsyncSelect from "react-select/lib/Async";
class FormFilter extends Component {
constructor(props) {
super(props);
this.state = {
inputValue: "",
selectedOption: "",
genres: []
};
}
selectGenreHandleChange = newValue => {
const inputValue = newValue.replace(/\W/g, "");
this.setState({ inputValue });
console.log(inputValue);
};
componentDidMount() {
this.genresOption();
}
filterGenres = inputValue => {
const genres = this.genresOption();
//HERE - return the filter
return genres.filter(genre =>
genre.label.toLowerCase().includes(inputValue.toLowerCase())
);
};
promiseOptions = inputValue => {
return new Promise(resolve => { // HERE - you have to return the promise
setTimeout(() => {
resolve(this.filterGenres(inputValue));
}, 1000);
});
};
genresOption() {
const options = [];
const genres = this.props.genresList.genres; //HERE - array is genres in genresList
if (genres && genres instanceof Array) {
genres.map(genre => options.push({ value: genre.id, label: genre.name}));
}
return options;
}
render() {
const { inputValue } = this.state;
if (this.state.genres) console.log("state", this.state.genres);
if (this.props.genresList)
console.log("Movies props", this.props.genresList);
return (
<div className="filter_form">
<span className="search_element full">
<label htmlFor="genres">Genres</label>
<AsyncSelect
className="select genres"
classNamePrefix="tmdb_select"
isMulti
isSearchable="true"
isClearable="true"
cacheOptions
components={Animated}
value={inputValue}
defaultOptions
onInputChange={this.selectGenreHandleChange}
loadOptions={this.promiseOptions}
/>
</span>
</div>
);
}
}
export default FormFilter;
I have write a comment "HERE - something" to let you know what I changed. There are not big problems :)

I did some changed in your FIDDLE and it's works for me
Something like
import React, {Component} from "react";
import { render } from 'react-dom';
import Movies from './Movies';
import "./styles.css";
class App extends Component {
render() {
return (
<div className="App">
<Movies />
</div>
);
}
}
let a = document.getElementById("root");
render(<App />, a);