I want to build a chat system and automatically scroll to the bottom when entering the window and when new messages come in. How do you automatically scroll to the bottom of a container in React?
As Tushar mentioned, you can keep a dummy div at the bottom of your chat:
render () {
return (
<div>
<div className="MessageContainer" >
<div className="MessagesList">
{this.renderMessages()}
</div>
<div style={{ float:"left", clear: "both" }}
ref={(el) => { this.messagesEnd = el; }}>
</div>
</div>
</div>
);
}
and then scroll to it whenever your component is updated (i.e. state updated as new messages are added):
scrollToBottom = () => {
this.messagesEnd.scrollIntoView({ behavior: "smooth" });
}
componentDidMount() {
this.scrollToBottom();
}
componentDidUpdate() {
this.scrollToBottom();
}
I'm using the standard Element.scrollIntoView method here.
I just want to update the answer to match the new React.createRef() method, but it's basically the same, just have in mind the current property in the created ref:
class Messages extends React.Component {
const messagesEndRef = React.createRef()
componentDidMount () {
this.scrollToBottom()
}
componentDidUpdate () {
this.scrollToBottom()
}
scrollToBottom = () => {
this.messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' })
}
render () {
const { messages } = this.props
return (
<div>
{messages.map(message => <Message key={message.id} {...message} />)}
<div ref={this.messagesEndRef} />
</div>
)
}
}
UPDATE:
Now that hooks are available, I'm updating the answer to add the use of the useRef and useEffect hooks, the real thing doing the magic (React refs and scrollIntoView DOM method) remains the same:
import React, { useEffect, useRef } from 'react'
const Messages = ({ messages }) => {
const messagesEndRef = useRef(null)
const scrollToBottom = () => {
messagesEndRef.current?.scrollIntoView({ behavior: "smooth" })
}
useEffect(() => {
scrollToBottom()
}, [messages]);
return (
<div>
{messages.map(message => <Message key={message.id} {...message} />)}
<div ref={messagesEndRef} />
</div>
)
}
Also made a (very basic) codesandbox if you wanna check the behaviour https://codesandbox.io/s/scrolltobottomexample-f90lz
Do not use findDOMNode
Class components with ref
class MyComponent extends Component {
componentDidMount() {
this.scrollToBottom();
}
componentDidUpdate() {
this.scrollToBottom();
}
scrollToBottom() {
this.el.scrollIntoView({ behavior: 'smooth' });
}
render() {
return <div ref={el => { this.el = el; }} />
}
}
Function components with hooks:
import React, { useRef, useEffect } from 'react';
const MyComponent = () => {
const divRef = useRef(null);
useEffect(() => {
divRef.current.scrollIntoView({ behavior: 'smooth' });
});
return <div ref={divRef} />;
}
Thanks to #enlitement
we should avoid using findDOMNode,
we can use refs to keep track of the components
render() {
...
return (
<div>
<div
className="MessageList"
ref={(div) => {
this.messageList = div;
}}
>
{ messageListContent }
</div>
</div>
);
}
scrollToBottom() {
const scrollHeight = this.messageList.scrollHeight;
const height = this.messageList.clientHeight;
const maxScrollTop = scrollHeight - height;
this.messageList.scrollTop = maxScrollTop > 0 ? maxScrollTop : 0;
}
componentDidUpdate() {
this.scrollToBottom();
}
reference:
https://facebook.github.io/react/docs/react-dom.html#finddomnode
https://www.pubnub.com/blog/2016-06-28-reactjs-chat-app-infinite-scroll-history-using-redux/
The easiest and best way I would recommend is.
My ReactJS version: 16.12.0
For Class Components
HTML structure inside render() function
render()
return(
<body>
<div ref="messageList">
<div>Message 1</div>
<div>Message 2</div>
<div>Message 3</div>
</div>
</body>
)
)
scrollToBottom() function which will get reference of the element.
and scroll according to scrollIntoView() function.
scrollToBottom = () => {
const { messageList } = this.refs;
messageList.scrollIntoView({behavior: "smooth", block: "end", inline: "nearest"});
}
and call the above function inside componentDidMount() and componentDidUpdate()
For Functional Components (Hooks)
Import useRef() and useEffect()
import { useEffect, useRef } from 'react'
Inside your export function, (same as calling a useState())
const messageRef = useRef();
And let's assume you have to scroll when page load,
useEffect(() => {
if (messageRef.current) {
messageRef.current.scrollIntoView(
{
behavior: 'smooth',
block: 'end',
inline: 'nearest'
})
}
})
OR if you want it to trigger once an action performed,
useEffect(() => {
if (messageRef.current) {
messageRef.current.scrollIntoView(
{
behavior: 'smooth',
block: 'end',
inline: 'nearest'
})
}
},
[stateVariable])
And Finally, to your HTML structure
return(
<body>
<div ref={messageRef}> // <= The only different is we are calling a variable here
<div>Message 1</div>
<div>Message 2</div>
<div>Message 3</div>
</div>
</body>
)
for more explanation about Element.scrollIntoView() visit developer.mozilla.org
More detailed explanation in Callback refs visit reactjs.org
react-scrollable-feed automatically scrolls down to the latest element if the user was already at the bottom of the scrollable section. Otherwise, it will leave the user at the same position. I think this is pretty useful for chat components :)
I think the other answers here will force scroll everytime no matter where the scrollbar was. The other issue with scrollIntoView is that it will scroll the whole page if your scrollable div was not in view.
It can be used like this :
import * as React from 'react'
import ScrollableFeed from 'react-scrollable-feed'
class App extends React.Component {
render() {
const messages = ['Item 1', 'Item 2'];
return (
<ScrollableFeed>
{messages.map((message, i) => <div key={i}>{message}</div>)}
</ScrollableFeed>
);
}
}
Just make sure to have a wrapper component with a specific height or max-height
Disclaimer: I am the owner of the package
I could not get any of below answers to work but simple js did the trick for me:
window.scrollTo({
top: document.body.scrollHeight,
left: 0,
behavior: 'smooth'
});
If you want to do this with React Hooks, this method can be followed. For a dummy div has been placed at the bottom of the chat. useRef Hook is used here.
Hooks API Reference : https://reactjs.org/docs/hooks-reference.html#useref
import React, { useEffect, useRef } from 'react';
const ChatView = ({ ...props }) => {
const el = useRef(null);
useEffect(() => {
el.current.scrollIntoView({ block: 'end', behavior: 'smooth' });
});
return (
<div>
<div className="MessageContainer" >
<div className="MessagesList">
{this.renderMessages()}
</div>
<div id={'el'} ref={el}>
</div>
</div>
</div>
);
}
There are two major problems with the scrollIntoView(...) approach in the top answers:
it's semantically incorrect, as it causes the entire page to scroll if your parent element is scrolled outside the window boundaries. The browser literally scrolls anything it needs to in getting the element visible.
in a functional component using useEffect(), you get unreliable results, at least in Chrome 96.0.4665.45. useEffect() gets called too soon on page reload and the scroll doesn't happen. Delaying scrollIntoView with setTimeout(..., 0) fixes it for page reload, but not first load in a fresh tab, at least for me. shrugs
Here's the solution I've been using, it's solid and is more compatible with older browsers:
function Chat() {
const chatParent = useRef<HTMLDivElement(null);
useEffect(() => {
const domNode = chatParent.current;
if (domNode) {
domNode.scrollTop = domNode.scrollHeight;
}
})
return (
<div ref={chatParent}>
...
</div>
)
}
You can use refs to keep track of the components.
If you know of a way to set the ref of one individual component (the last one), please post!
Here's what I found worked for me:
class ChatContainer extends React.Component {
render() {
const {
messages
} = this.props;
var messageBubbles = messages.map((message, idx) => (
<MessageBubble
key={message.id}
message={message.body}
ref={(ref) => this['_div' + idx] = ref}
/>
));
return (
<div>
{messageBubbles}
</div>
);
}
componentDidMount() {
this.handleResize();
// Scroll to the bottom on initialization
var len = this.props.messages.length - 1;
const node = ReactDOM.findDOMNode(this['_div' + len]);
if (node) {
node.scrollIntoView();
}
}
componentDidUpdate() {
// Scroll as new elements come along
var len = this.props.messages.length - 1;
const node = ReactDOM.findDOMNode(this['_div' + len]);
if (node) {
node.scrollIntoView();
}
}
}
Reference your messages container.
<div ref={(el) => { this.messagesContainer = el; }}> YOUR MESSAGES </div>
Find your messages container and make its scrollTop attribute equal scrollHeight:
scrollToBottom = () => {
const messagesContainer = ReactDOM.findDOMNode(this.messagesContainer);
messagesContainer.scrollTop = messagesContainer.scrollHeight;
};
Evoke above method on componentDidMount and componentDidUpdate.
componentDidMount() {
this.scrollToBottom();
}
componentDidUpdate() {
this.scrollToBottom();
}
This is how I am using this in my code:
export default class StoryView extends Component {
constructor(props) {
super(props);
this.scrollToBottom = this.scrollToBottom.bind(this);
}
scrollToBottom = () => {
const messagesContainer = ReactDOM.findDOMNode(this.messagesContainer);
messagesContainer.scrollTop = messagesContainer.scrollHeight;
};
componentDidMount() {
this.scrollToBottom();
}
componentDidUpdate() {
this.scrollToBottom();
}
render() {
return (
<div>
<Grid className="storyView">
<Row>
<div className="codeView">
<Col md={8} mdOffset={2}>
<div ref={(el) => { this.messagesContainer = el; }}
className="chat">
{
this.props.messages.map(function (message, i) {
return (
<div key={i}>
<div className="bubble" >
{message.body}
</div>
</div>
);
}, this)
}
</div>
</Col>
</div>
</Row>
</Grid>
</div>
);
}
}
I created a empty element in the end of messages, and scrolled to that element. No need of keeping track of refs.
Working Example:
You can use the DOM scrollIntoView method to make a component visible in the view.
For this, while rendering the component just give a reference ID for the DOM element using ref attribute. Then use the method scrollIntoView on componentDidMount life cycle. I am just putting a working sample code for this solution. The following is a component rendering each time a message received. You should write code/methods for rendering this component.
class ChatMessage extends Component {
scrollToBottom = (ref) => {
this.refs[ref].scrollIntoView({ behavior: "smooth" });
}
componentDidMount() {
this.scrollToBottom(this.props.message.MessageId);
}
render() {
return(
<div ref={this.props.message.MessageId}>
<div>Message content here...</div>
</div>
);
}
}
Here this.props.message.MessageId is the unique ID of the particular chat message passed as props
import React, {Component} from 'react';
export default class ChatOutPut extends Component {
constructor(props) {
super(props);
this.state = {
messages: props.chatmessages
};
}
componentDidUpdate = (previousProps, previousState) => {
if (this.refs.chatoutput != null) {
this.refs.chatoutput.scrollTop = this.refs.chatoutput.scrollHeight;
}
}
renderMessage(data) {
return (
<div key={data.key}>
{data.message}
</div>
);
}
render() {
return (
<div ref='chatoutput' className={classes.chatoutputcontainer}>
{this.state.messages.map(this.renderMessage, this)}
</div>
);
}
}
thank you 'metakermit' for his good answer, but I think we can make it a bit better,
for scroll to bottom, we should use this:
scrollToBottom = () => {
this.messagesEnd.scrollIntoView({ behavior: "smooth", block: "end", inline: "nearest" });
}
but if you want to scroll top, you should use this:
scrollToTop = () => {
this.messagesEnd.scrollIntoView({ behavior: "smooth", block: "start", inline: "nearest" });
}
and this codes are common:
componentDidMount() {
this.scrollToBottom();
}
componentDidUpdate() {
this.scrollToBottom();
}
render () {
return (
<div>
<div className="MessageContainer" >
<div className="MessagesList">
{this.renderMessages()}
</div>
<div style={{ float:"left", clear: "both" }}
ref={(el) => { this.messagesEnd = el; }}>
</div>
</div>
</div>
);
}
As another option it is worth looking at react scroll component.
I like doing it the following way.
componentDidUpdate(prevProps, prevState){
this.scrollToBottom();
}
scrollToBottom() {
const {thing} = this.refs;
thing.scrollTop = thing.scrollHeight - thing.clientHeight;
}
render(){
return(
<div ref={`thing`}>
<ManyThings things={}>
</div>
)
}
This is how you would solve this in TypeScript (using the ref to a targeted element where you scroll to):
class Chat extends Component <TextChatPropsType, TextChatStateType> {
private scrollTarget = React.createRef<HTMLDivElement>();
componentDidMount() {
this.scrollToBottom();//scroll to bottom on mount
}
componentDidUpdate() {
this.scrollToBottom();//scroll to bottom when new message was added
}
scrollToBottom = () => {
const node: HTMLDivElement | null = this.scrollTarget.current; //get the element via ref
if (node) { //current ref can be null, so we have to check
node.scrollIntoView({behavior: 'smooth'}); //scroll to the targeted element
}
};
render <div>
{message.map((m: Message) => <ChatMessage key={`chat--${m.id}`} message={m}/>}
<div ref={this.scrollTarget} data-explanation="This is where we scroll to"></div>
</div>
}
For more information about using ref with React and Typescript you can find a great article here.
This works for me
messagesEndRef.current.scrollTop = messagesEndRef.current.scrollHeight
where const messagesEndRef = useRef(); to use
Using React.createRef()
class MessageBox extends Component {
constructor(props) {
super(props)
this.boxRef = React.createRef()
}
scrollToBottom = () => {
this.boxRef.current.scrollTop = this.boxRef.current.scrollHeight
}
componentDidUpdate = () => {
this.scrollToBottom()
}
render() {
return (
<div ref={this.boxRef}></div>
)
}
}
This is modified from an answer above to support 'children' instead of a data array.
Note: The use of styled-components is of no importance to the solution.
import {useEffect, useRef} from "react";
import React from "react";
import styled from "styled-components";
export interface Props {
children: Array<any> | any,
}
export function AutoScrollList(props: Props) {
const bottomRef: any = useRef();
const scrollToBottom = () => {
bottomRef.current.scrollIntoView({
behavior: "smooth",
block: "start",
});
};
useEffect(() => {
scrollToBottom()
}, [props.children])
return (
<Container {...props}>
<div key={'child'}>{props.children}</div>
<div key={'dummy'} ref={bottomRef}/>
</Container>
);
}
const Container = styled.div``;
In order to scroll down to the bottom of the page first we have to select an id which resides at the bottom of the page. Then we can use the document.getElementById to select the id and scroll down using scrollIntoView(). Please refer the below code.
scrollToBottom= async ()=>{
document.getElementById('bottomID').scrollIntoView();
}
I have face this problem in mweb/web.All the solution is good in this page but all the solution is not working while using android chrome browser .
So for mweb and web I got the solution with some minor fixes.
import { createRef, useEffect } from 'react';
import { useSelector } from 'react-redux';
import { AppState } from 'redux/store';
import Message from '../Message/Message';
import styles from './MessageList.module.scss';
const MessageList = () => {
const messagesEndRef: any = createRef();
const { messages } = useSelector((state: AppState) => state?.video);
const scrollToBottom = () => {
//this is not working in mWeb
// messagesEndRef.current.scrollIntoView({
// behavior: 'smooth',
// block: 'end',
// inline: 'nearest',
// });
const scroll =
messagesEndRef.current.scrollHeight -
messagesEndRef.current.clientHeight;
messagesEndRef.current.scrollTo(0, scroll);
};
useEffect(() => {
if (messages.length > 3) {
scrollToBottom();
}
}, [messages]);
return (
<section className={styles.footerTopSection} ref={messagesEndRef} >
{messages?.map((message: any) => (
<Message key={message.id} {...message} />
))}
</section>
);
};
export default MessageList;
This is a great usecase for useLayoutEffect as taught by Kent C. Dodds.
https://kentcdodds.com/blog/useeffect-vs-uselayouteffect
if your effect is mutating the DOM (via a DOM node ref) and the DOM mutation will change the appearance of the DOM node between the time that it is rendered and your effect mutates it, then you don't want to use useEffect.
In my case i was dynamically generating elements at the bottom of a div so i had to add a small timeout.
const bottomRef = useRef<null | HTMLDivElement>(null);
useLayoutEffect(() => {
setTimeout(function () {
if (bottomRef.current) bottomRef.current.scrollTop = bottomRef.current.scrollHeight;
}, 10);
}, [transactionsAmount]);
const scrollingBottom = () => {
const e = ref;
e.current?.scrollIntoView({
behavior: "smooth",
block: "center",
inline: "start",
});
};
useEffect(() => {
scrollingBottom();
});
<span ref={ref}>{item.body.content}</span>
Full version (Typescript):
import * as React from 'react'
export class DivWithScrollHere extends React.Component<any, any> {
loading:any = React.createRef();
componentDidMount() {
this.loading.scrollIntoView(false);
}
render() {
return (
<div ref={e => { this.loading = e; }}> <LoadingTile /> </div>
)
}
}
Related
I am trying to implement a condition in my react component . When the user triggers the onClick the state updates allStakes creating one array of 4 values. The problem is that I do not want the user to input more than 4 values so tried to give the limit by doing an if else statement. I tried to add a console.log in both statements.The weird fact is that setState get updated but the csonole.log is never displayed.The component keeps rendering all the values that I insert even if the array is longer than 4. Thanks in advance
import React, { Component } from 'react';
import Stake from './stake';
class FetchRandomBet extends Component {
constructor(props) {
super(props);
this.state = {
loading: true,
bet: null,
value: this.props.value,
allStakes: []
};
}
async componentDidMount() {
const url = "http://localhost:4000/";
const response = await fetch(url);
const data = await response.json();
this.setState({
loading: false,
bet: data.bets,
});
}
render() {
const { valueProp: value } = this.props;
const { bet, loading } = this.state;
const { allStakes } = this.state;
if (loading) {
return <div>loading..</div>;
}
if (!bet) {
return <div>did not get data</div>;
}
return (
< div >
{
loading || !bet ? (
<div>loading..</div>
) : value === 0 ? (
<div className="bet-list">
<ol>
<p>NAME</p>
{
bet.map(post => (
<li key={post.id}>
{post.name}
</li>
))
}
</ol>
<ul>
<p>ODDS</p>
{
bet.map(post => (
<li key={post.id}>
{post.odds[4].oddsDecimal}
<div className="stake-margin">
<Stake
onClick={(newStake) => {
if (allStakes.length <= 3) {
this.setState({ allStakes: [allStakes, ...newStake] })
console.log('stop')
} else if (allStakes.length == 4) {
console.log('more than 3')
}
}}
/>
</div>
</li>
))
}
</ul>
</div>
May be it happens because of incorrect array destructuring. Try to change this code:
this.setState({ allStakes: [allStakes, ...newStake] })
by the next one:
this.setState({ allStakes: [newStake, ...allStakes] })
Your state belongs to your FetchRandomBet component and you are trying to update that from your imported component. There are 2 solutions to that.
1> Wrap your Stake component to a separate component with onClick handler something like this
<div onClick={(newStake) => {
if (allStakes.length <= 3) {
this.setState({
allStakes: [allStakes, ...newStake
]
})
console.log('stop')
} else if (allStakes.length == 4) {
console.log('more than 3')
}
}}><Stake /></div>
Or
2> Pass the state as a prop to the Stake component which will be responsible to update the state for FetchRandomBet. something like this
<Stake parentState={this}/>
And inside the Stake component change the parentState on click of wherever you want.
I solved the problem. I transfered the onClick method in stake component and I handled the upload of the common array with an array useState. I add the value to newStake and when I click ok I retrieve newStake and spread it into a new array and then I check that array. If there is a value should not keep adding otherwise it can add values. It works fine. Thanks anyway
import React, { useState } from 'react';
import CurrencyInput from 'react-currency-input-field';
function Stake(props) {
const [newStake, setStake] = useState(null);
const [allStakes, setStakes] = useState(null);
const changeStake = (e) => {
setStake([e.target.value])
}
const mySubmit = () => {
if (!allStakes) {
setStakes([...newStake, allStakes])
props.onClick(newStake);
} else if (allStakes) {
console.log('stop')
}
}
return (
<>
<CurrencyInput
onChange={changeStake}
style={{
marginLeft: "40px",
width: "50px"
}}
placeholder="Stake"
decimalScale={2}
prefix="£"
/>
<button onClick={mySubmit}>yes</button>
<button>no</button>
{newStake}
</>
);
}
export default Stake;
I am bulding an app using newsapi. i am facing two issue on my state. i fetch data using api and assign it to my state. and use it in my view.
Issue no 1
My view gets rendered before my app receives the data.
Issue no 2
When I try to update my state after a new fetch. it recursively updates the set of data again and again.
import React, {Component} from 'react';
import NewsComponent from './NewsComponent/NewsComponent'
class News extends Component {
state = {
displayStatus: false,
newsItems: []
};
toogleDisplayHandler = () => {
if(this.state.displayStatus===true){
this.setState({displayStatus:false})
}
else{
this.setState({displayStatus:true})
}
}
render(){
const NewsAPI = require('newsapi');
const newsapi = new NewsAPI('d6da863f882e4a1a89c5152bd3692fb6');
//console.log(this.props.keyword);
newsapi.v2.topHeadlines({
sources: 'bbc-news,abc-news',
q: this.props.keyword
}).then(response => {
//console.log(response)
response.articles.map(article => {
//console.log(article);
return(
//console.log(this.state.newsItems)
this.setState({
newsItems: [...this.state.newsItems, article],
})
//this.state.newsItems.push(article)
)
});
});
let Article = null;
Article = (
<div>
{
this.state.newsItems.map((news, index) => {
return (
<NewsComponent key={index}
title={news.title}
url={news.url}
description={news.description}
author={news.author}
publish={news.publishedAt}
image={news.urlToImage}
/>
)
})
}
</div>
)
return (
<div className="App">
{Article}
<button onClick={this.toogleDisplayHandler}>
{this.state.displayStatus === true ? "Hide Article" : "Display Articles"}
</button>
</div>
)
}
}
export default News;
Please help me to resolve this issue.
You should never setState in render as that would cause an infinite loop. Do it in componentDidMount or the constructor.
I would also recommend not using map for simply iterating over a list. Array.map is a function that is useful for returning an array that is constructed by iterating over another array. If you want to run some code for each element of an array use Array.forEach instead.
Like this:
import React, { Component } from "react";
import NewsComponent from "./NewsComponent/NewsComponent";
class News extends Component {
state = {
displayStatus: false,
newsItems: []
};
toogleDisplayHandler = () => {
if (this.state.displayStatus === true) {
this.setState({ displayStatus: false });
} else {
this.setState({ displayStatus: true });
}
};
componentDidMount = () => {
const NewsAPI = require("newsapi");
const newsapi = new NewsAPI("d6da863f882e4a1a89c5152bd3692fb6");
newsapi.v2
.topHeadlines({
sources: "bbc-news,abc-news",
q: this.props.keyword
})
.then(response => {
response.articles.forEach(article => {
this.setState({
newsItems: [...this.state.newsItems, article]
});
});
});
};
render() {
let Article = null;
Article = (
<div>
{this.state.newsItems.map((news, index) => {
return (
<NewsComponent
key={index}
title={news.title}
url={news.url}
description={news.description}
author={news.author}
publish={news.publishedAt}
image={news.urlToImage}
/>
);
})}
</div>
);
return (
<div className="App">
{Article}
<button onClick={this.toogleDisplayHandler}>
{this.state.displayStatus === true
? "Hide Article"
: "Display Articles"}
</button>
</div>
);
}
}
export default News;
1) You can add a check either your state has the data which you want to show on screen to render the view.
2) Please use ComponentDidMount React life cycle function to fetch data from an external source and update this data in the state. In the Render method, it will keep calling it recursively.
I am really new in React.js. I wanna pass a state (that i set from api data before) to a component so value of selectable list can dynamically fill from my api data. Here is my code for fetching data :
getListSiswa(){
fetch('http://localhost/assessment-app/adminpg/api/v1/Siswa/')
.then(posts => {
return posts.json();
}).then(data => {
let item = data.posts.map((itm) => {
return(
<div key={itm.siswa_id}>
<ListItem
value={itm.siswa_id}
primaryText={itm.nama}
/>
</div>
)
});
this.setState({item: item});
});
}
From that code, i set a state called item. And i want to pass this state to a component. Here is my code :
const ListSiswa = () => (
<SelectableList>
<Subheader>Daftar Siswa</Subheader>
{this.state.item}
</SelectableList>
);
But i get an error that say
TypeError: Cannot read property 'item' of undefined
I am sorry for my bad explanation. But if you get my point, i am really looking forward for your solution.
Here is my full code for additional info :
import React, {Component} from 'react';
import PropTypes from 'prop-types';
import {List, ListItem, makeSelectable} from 'material-ui/List';
import Subheader from 'material-ui/Subheader';
let SelectableList = makeSelectable(List);
function wrapState(ComposedComponent) {
return class SelectableList extends Component {
static propTypes = {
children: PropTypes.node.isRequired,
};
getListSiswa(){
fetch('http://localhost/assessment-app/adminpg/api/v1/Siswa/')
.then(posts => {
return posts.json();
}).then(data => {
let item = data.posts.map((itm) => {
return(
<div key={itm.siswa_id}>
<ListItem
value={itm.siswa_id}
primaryText={itm.nama}
/>
</div>
)
});
this.setState({item: item});
});
}
componentWillMount() {
this.setState({
selectedIndex: this.props.defaultValue,
});
this.getListSiswa();
}
handleRequestChange = (event, index) => {
this.setState({
selectedIndex: index,
});
};
render() {
console.log(this.state.item);
return (
<ComposedComponent
value={this.state.selectedIndex}
onChange={this.handleRequestChange}
>
{this.props.children}
</ComposedComponent>
);
}
};
}
SelectableList = wrapState(SelectableList);
const ListSiswa = () => (
<SelectableList>
<Subheader>Daftar Siswa</Subheader>
{this.state.item}
</SelectableList>
);
export default ListSiswa;
One way to do it is by having the state defined in the parent component instead and pass it down to the child via props:
let SelectableList = makeSelectable(List);
function wrapState(ComposedComponent) {
return class SelectableList extends Component {
static propTypes = {
children: PropTypes.node.isRequired,
};
componentWillMount() {
this.setState({
selectedIndex: this.props.defaultValue,
});
this.props.fetchItem();
}
handleRequestChange = (event, index) => {
this.setState({
selectedIndex: index,
});
};
render() {
console.log(this.state.item);
return (
<ComposedComponent
value={this.state.selectedIndex}
onChange={this.handleRequestChange}
>
{this.props.children}
{this.props.item}
</ComposedComponent>
);
}
};
}
SelectableList = wrapState(SelectableList);
class ListSiswa extends Component {
state = {
item: {}
}
getListSiswa(){
fetch('http://localhost/assessment-app/adminpg/api/v1/Siswa/')
.then(posts => {
return posts.json();
}).then(data => {
let item = data.posts.map((itm) => {
return(
<div key={itm.siswa_id}>
<ListItem
value={itm.siswa_id}
primaryText={itm.nama}
/>
</div>
)
});
this.setState({item: item});
});
}
render() {
return (
<SelectableList item={this.state.item} fetchItem={this.getListSiswa}>
<Subheader>Daftar Siswa</Subheader>
</SelectableList>
);
}
}
export default ListSiswa;
Notice that in wrapState now I'm accessing the state using this.props.item and this.props.fetchItem. This practice is also known as prop drilling in React and it will be an issue once your app scales and multiple nested components. For scaling up you might want to consider using Redux or the Context API. Hope that helps!
The error is in this component.
const ListSiswa = () => (
<SelectableList>
<Subheader>Daftar Siswa</Subheader>
{this.state.item}
</SelectableList>
);
This component is referred as Stateless Functional Components (Read)
It is simply a pure function which receives some data and returns the jsx.
you do not have the access this here.
I have used ReactDOM.createPortal inside the render method of a stateful component like so:
class MyComponent extends Component {
...
render() {
return (
<Wrapper>
{ReactDOM.createPortal(<FOO />, 'dom-location')}
</Wrapper>
)
}
}
... but can it also be used by a stateless (functional) component?
Will chime in with an option where you dont want to manually update your index.html and add extra markup, this snippet will dynamically create a div for you, then insert the children.
export const Portal = ({ children, className = 'root-portal', el = 'div' }) => {
const [container] = React.useState(() => {
// This will be executed only on the initial render
// https://reactjs.org/docs/hooks-reference.html#lazy-initial-state
return document.createElement(el);
});
React.useEffect(() => {
container.classList.add(className)
document.body.appendChild(container)
return () => {
document.body.removeChild(container)
}
}, [])
return ReactDOM.createPortal(children, container)
}
It can be done like this for a fixed component:
const MyComponent = () => ReactDOM.createPortal(<FOO/>, 'dom-location')
or, to make the function more flexible, by passing a component prop:
const MyComponent = ({ component }) => ReactDOM.createPortal(component, 'dom-location')
can it also be used by a stateless (functional) component
?
yes.
const Modal = (props) => {
const modalRoot = document.getElementById('myEle');
return ReactDOM.createPortal(props.children, modalRoot,);
}
Inside render :
render() {
const modal = this.state.showModal ? (
<Modal>
<Hello/>
</Modal>
) : null;
return (
<div>
<div id="myEle">
</div>
</div>
);
}
Working codesandbox#demo
TSX version based on #Samuel's answer (React 17, TS 4.1):
// portal.tsx
import * as React from 'react'
import * as ReactDOM from 'react-dom'
interface IProps {
className? : string
el? : string
children : React.ReactNode
}
/**
* React portal based on https://stackoverflow.com/a/59154364
* #param children Child elements
* #param className CSS classname
* #param el HTML element to create. default: div
*/
const Portal : React.FC<IProps> = ( { children, className, el = 'div' } : IProps ) => {
const [container] = React.useState(document.createElement(el))
if ( className )
container.classList.add(className)
React.useEffect(() => {
document.body.appendChild(container)
return () => {
document.body.removeChild(container)
}
}, [])
return ReactDOM.createPortal(children, container)
}
export default Portal
IMPORTANT useRef/useState to prevent bugs
It's important that you use useState or useRef to store the element you created via document.createElement because otherwise it gets recreated on every re-render
//This div with id of "overlay-portal" needs to be added to your index.html or for next.js _document.tsx
const modalRoot = document.getElementById("overlay-portal")!;
//we use useRef here to only initialize el once and not recreate it on every rerender, which would cause bugs
const el = useRef(document.createElement("div"));
useEffect(() => {
modalRoot.appendChild(el.current);
return () => {
modalRoot.removeChild(el.current);
};
}, []);
return ReactDOM.createPortal(
<div
onClick={onOutSideClick}
ref={overlayRef}
className={classes.overlay}
>
<div ref={imageRowRef} className={classes.fullScreenImageRow}>
{renderImages()}
</div>
<button onClick={onClose} className={classes.closeButton}>
<Image width={25} height={25} src="/app/close-white.svg" />
</button>
</div>,
el.current
);
Yes, according to docs the main requirements are:
The first argument (child) is any renderable React child, such as an element, string, or fragment. The second argument (container) is a DOM element.
In case of stateless component you can pass element via props and render it via portal.
Hope it will helps.
Portal with SSR (NextJS)
If you are trying to use any of the above with SSR (for example NextJS) you may run into difficulty.
The following should get you what you need. This methods allows for passing in an id/selector to use for the portal which can be helpful in some cases, otherwise it creates a default using __ROOT_PORTAL__.
If it can't find the selector then it will create and attach a div.
NOTE: you could also statically add a div and specify a known id in pages/_document.tsx (or .jsx) if again using NextJS. Pass in that id and it will attempt to find and use it.
import { PropsWithChildren, useEffect, useState, useRef } from 'react';
import { createPortal } from 'react-dom';
export interface IPortal {
selector?: string;
}
const Portal = (props: PropsWithChildren<IPortal>) => {
props = {
selector: '__ROOT_PORTAL__',
...props
};
const { selector, children } = props;
const ref = useRef<Element>()
const [mounted, setMounted] = useState(false);
const selectorPrefixed = '#' + selector.replace(/^#/, '');
useEffect(() => {
ref.current = document.querySelector(selectorPrefixed);
if (!ref.current) {
const div = document.createElement('div');
div.setAttribute('id', selector);
document.body.appendChild(div);
ref.current = div;
}
setMounted(true);
}, [selector]);
return mounted ? createPortal(children, ref.current) : null;
};
export default Portal;
Usage
The below is a quickie example of using the portal. It does NOT take into account position etc. Just something simple to show you usage. Sky is limit from there :)
import React, { useState, CSSProperties } from 'react';
import Portal from './path/to/portal'; // Path to above
const modalStyle: CSSProperties = {
padding: '3rem',
backgroundColor: '#eee',
margin: '0 auto',
width: 400
};
const Home = () => {
const [visible, setVisible] = useState(false);
return (
<>
<p>Hello World <a href="#" onClick={() => setVisible(true)}>Show Modal</a></p>
<Portal>
{visible ? <div style={modalStyle}>Hello Modal! <a href="#" onClick={() => setVisible(false)}>Close</a></div> : null}
</Portal>
</>
);
};
export default Home;
const X = ({ children }) => ReactDOM.createPortal(children, 'dom-location')
Sharing my solution:
// PortalWrapperModal.js
import React, { useRef, useEffect } from 'react';
import ReactDOM from 'react-dom';
import $ from 'jquery';
const PortalWrapperModal = ({
children,
onHide,
backdrop = 'static',
focus = true,
keyboard = false,
}) => {
const portalRef = useRef(null);
const handleClose = (e) => {
if (e) e.preventDefault();
if (portalRef.current) $(portalRef.current).modal('hide');
};
useEffect(() => {
if (portalRef.current) {
$(portalRef.current).modal({ backdrop, focus, keyboard });
$(portalRef.current).modal('show');
$(portalRef.current).on('hidden.bs.modal', onHide);
}
}, [onHide, backdrop, focus, keyboard]);
return ReactDOM.createPortal(
<>{children(portalRef, handleClose)}</>,
document.getElementById('modal-root')
);
};
export { PortalWrapperModal };
I try to animate a div with reactjs using async data via redux and it's not clear to me when can I have a reference to the virtual dom on state loaded.
In my case I have a div with id header where I would like to push down the container when data was populated.
If I try in componentDidMount than I get Cannot read property 'style' of undefined because componentDidMount still having a reference to an on load container
class HomePage extends React.Component {
constructor(props) {
super(props);
this.state = {
sliderLength: null
}
}
componentDidMount() {
this.props.actions.getSlides()
if(this.header) {
setTimeout(function() {
this.header.style.bottom = -(this.header.clientHeight - 40) + 'px';
}, 2000);
}
//header.style.bottom = -pushBottom+'px';
}
componentWillReceiveProps(nextProps) {
let {loaded} = nextProps
if(loaded === true ) {
this.animateHeader()
}
}
animateHeader() {
}
componentWillMount() {
const {slides} = this.props;
this.setState({
sliderLength: slides.length,
slides: slides
});
}
render() {
const {slides, post, loaded} = this.props;
if(loaded ===true ) {
let sliderTeaser = _.map(slides, function (slide) {
if(slide.status === 'publish') {
return <Link key={slide.id} to={'portfolio/' + slide.slug}><img key={slide.id} className="Img__Teaser" src={slide.featured_image_url.full} /></Link>
}
});
let about = _.map(post, function (data) {
return data.content.rendered;
})
return (
<div className="homePage">
<Slider columns={1} autoplay={true} post={post} slides={slides} />
<div id="header" ref={ (header) => this.header = header}>
<div className="title">Title</div>
<div className="text-content">
<div dangerouslySetInnerHTML={createMarkup(about)}/>
</div>
<div className="sliderTeaser">
{sliderTeaser}
</div>
<div className="columns">
<div className="column"></div>
<div className="column"></div>
<div className="column"></div>
</div>
</div>
<div id="bgHover"></div>
</div>
);
} else {
return <div>...Loading</div>
}
}
}
function mapStateToProps(state) {
return {
slides: state.slides,
post: state.post,
loaded: state.loaded
};
}
function mapDispatchToProps(dispatch) {
return {
actions: bindActionCreators(slidesActions, dispatch)
};
}
function createMarkup(markup) {
return {__html: markup};
}
export default connect(mapStateToProps, mapDispatchToProps)(HomePage);
How do I deal in this case with states?
Between I found a solution but not sure if is the right workaround
componentDidUpdate() {
if(this.header) {
setTimeout(function() {
this.header.style.bottom = -(this.header.clientHeight - 35) + 'px';
}, 2000);
}
}
In general, try to avoid using ref as much as possible. This is particularly difficult if you're new to React but with some training, you'll find yourself not needing it.
The problem with modifying the styles like you're doing is that when the component will render again your changes will be overwritten.
I would create a new state property, say state.isHeaderOpen. In your render method you will render the header differently depending on the value of this header e.g.:
render () {
const {isHeaderOpen} = this.state
return (
<header style={{bottom: isHeaderOpen ? 0 : 'calc(100% - 40px)'}}>
)
}
Here I'm using calc with percentage values to get the full height of the header.
Next, in your componentDidMount simply update the state:
componentDidMount () {
setTimeout(() => this.setState({isHeaderOpen: false}), 2000);
}
In this way, the component will render again but with the updated style.
Another way is to check if the data has been loaded instead of creating a new state value. For example, say you're loading a list of users, in render you would write const isHeaderOpen = this.state.users != null.
If you are trying to animate a div why are you trying to access it by this.header just use the javaScript's plain old document.getElementById('header') and then you can play around with the div.