This error :
Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate. React limits the number of nested updates to prevent infinite loops.
why is this error?
import React, { Component } from 'react';
import './App.css';
class App extends Component {
constructor(props){
super(props);
this.state=({
todos:[],
})
this.add = this.add.bind(this);
this.remove = this.remove.bind(this);
}
//this.array.splice(2,1)
/*
let arrayy = [...this.state.array]
let removed = arrayy.splice(deger,1);
this.setState({
array:arrayy,
})
*/
add(){
const deger = document.getElementById('deger').value;
const todosarray = this.state.todos;
todosarray.push(deger)
this.setState({
todos:todosarray,
})
}
remove(num){
let arrayy = [...this.state.todos]
arrayy.splice(num,1)
this.setState({
array:arrayy,
})
}
render() {
const data = this.state.todos;
const listItems = data.map((result,i) => <li key={i} onClick={this.remove(i)}>{result }</li>);
return (
<div >
<input id="deger"></input>
<button onClick={this.add}>Add</button>
<div id="items">
{listItems}
</div>
</div>
);
}
}
export default App;
Replace this:
onClick={this.remove(i)}
By this:
onClick={() => this.remove(i)}
Explanation: while rendering, React evaluates this.remove(i), which changes the state or the props, thus triggering another render, and looping to re-evaluate this.remove(i); creating a (hidden) infinite loop. () => this.remove(i) is a function so the state or the props do not change. Also, it's probably what you wanted to code anyway ;)
Related
I have the following component:
import React from 'react';
import './styles.css';
import ToolTip from '../../Common/components/ToolTip/ToolTip';
export default class RouteTitleTooltipComponent extends React.Component {
constructor(props) {
super(props);
this.titleParagraphRef = React.createRef();
this._tooltipTimer = null;
this.state = { shouldPopupBeEnabled: false, isTooltipShown: false };
this._showTooltip = this._showTooltip.bind(this);
this._hideTooltip = this._hideTooltip.bind(this);
}
componentDidMount() {
const { scrollWidth, clientWidth } = this.titleParagraphRef.current;
const shouldPopupBeEnabled = scrollWidth > clientWidth;
this.setState({ shouldPopupBeEnabled });
}
_showTooltip() {
this._tooltipTimer = setTimeout(
() => {
this.setState({ isTooltipShown: true });
}, 1000,
);
}
_hideTooltip() {
clearTimeout(this._tooltipTimer);
this.setState({ isTooltipShown: false });
}
render() {
const { shouldPopupBeEnabled, isTooltipShown } = this.state;
const { message } = this.props;
return (
<ToolTip
message="Tooltip!!"
popoverOpen={shouldPopupBeEnabled && isTooltipShown}
>
<div
ref={this.titleParagraphRef}
onMouseOver={this._showTooltip}
>
{message}
</div>
</ToolTip>
);
}
}
This basically renders a floating tooltip over a div element if the message inside of it is bigger than the container. To do that, I use scrollWidth and clientWidth of the div element using a React reference. To detect those values I use componentDidMount, but this only works in full renders of the component. That is, if I have the component visible and reload the page, both values are equal to 0 and it does not work.
In addition, if I change the message, it does not work either because the component is already mounted.
So what I want is to change the state right after the component is mounted or updated so that the react reference is rendered and clientWidth and scrollWidth are not 0.
I have tried replace componentDidUpdate instead of componentDidMount but it's not a good practica to use setState inside componentDidUpdate.
Any solution?
First you should know that componentDidMount will execute only once. Therefor you can go for componentDidUpdate but don't forget to put a condition as it will render in a loop.
componentDidUpdate(prevProps,prevState) {
const shouldPopupBeEnabled = scrollWidth > clientWidth;
if (shouldPopupBeEnabled !== this.state.shouldPopupBeEnabled ) {
this.setState({shouldPopupBeEnabled });
}
}
Or you can go for functional components and use useEffect which will only render again if state changes.
useEffect(() => {
console.log('mounted');
}, [shouldPopupBeEnabled]) // It will re render id `shouldPopupBeEnabled` changes
I have a single page create-react-app project and the issue I am having is that the state is not updating. I have cut some of my code out just to make the example a bit shorter and easier to follow. The function where setState() is called is in form_change().
My goal here is to change the color of the text when there is an error, but even {this.state.test} isn't updating. I have tried putting console.log()s in various locations to get around the async nature of setState, but unfortunately they seem to show that state is never updated. It has been a while since I have used React, so there is a chance I am doing something very silly!
Thanks in advance for your help.
Here is my code:
import React,{Component} from 'react';
import './App.css';
import Dropdown from 'react-dropdown'
import classes from './classes.module.css'
import firebase from 'firebase';
import 'react-dropdown/style.css';
const axios = require('axios');
class App extends Component {
render(){
const error_empty = (param)=>{
if (this.state.error===undefined){
return false
}
else{
if (this.state.errors.find(el => el === param) === undefined){
return false
}
else return true
}
}
const form_change = (event, param)=>{
let form={...this.state.form};
form[param]=event.target.value;
let errors =verified(form);
console.log(form); //as expected
console.log(errors); //as expected
//works up til here. setState not updating for some reason.
this.setState({form:form,errors:errors,test:'Hello World'})
}
const verified = (data)=>{
let errors = [];
let form = data;
errors.push('ean')
return errors}
this.state = {
example:['abc'],
form:{
example:"abc"
}
}
return (
<div className="App">
<header className="App-header">
<div className={classes.button_holder}>
<div className={classes.page_button} onClick={()=>{null}}>
{this.state.test}
</div>
</div>
<div className={classes.user_form}>User Update Form
<div>
<input className={classes.input_text} style={{color: error_empty()?'red':'black'}} value={this.state.form.ean} onChange={(event)=>{form_change(event,'ean')}} placeholder={"EAN"}></input>
</div>
</div>
</header>
</div>
);
}
}
export default App;
Move initialization of state outside render function this.state.
Initialise your state in constructor
Don't update your state (this.setState) in render because this will lead to infinitive loop.
Move your functions error_empty(), form_change() and verified() outside the render.
To call function onChange use this
class App extends React.Component {
constructor(props) {
super(props);
this.state = {
example:['abc'],
form:{
example:"abc"
}
error: ""
}
}
error_empty = (param) => {
if(this.state.error===undefined) {
return false
}
else {
if(this.state.errors.find(el => el === param) === undefined) {
return false
}
return true
}
}
...
render() {
...
<input ... onChange={(event) => {this.form_change(event,'ean')}}/>
...
}
}
Layout.js
import React, {Component} from "react"
import Aircraft from "./Aircraft"
class Layout extends Component {
constructor(props) {
super(props)
this.state = {
test: true,
acn: ""
}
}
WhatIsAircraftName = (acn) => {
this.setState({
acn: acn
})
}
render() {
return (
<div>
<div className="mainD posRel hidO">
<div className="posRel hidO topD">
</div>
<div className="posRel hidO bottomD container">
<Aircraft clk={this.WhatIsAircraftName} />
</div>
</div>
</div>
)
}
}
export default Layout
Aircraft.js
import React, {Component} from "react"
import Loading from "./Loading"
class Aircraft extends Component {
constructor(props) {
super(props)
this.state = {
aircraft: [],
loading: false,
utilized: 0
}
}
componentDidMount() {
let mod_this = this
this.setState({
loading: true
})
fetch("https://some-endpoint")
.then(function(response) {
if (response.ok) {
return response.json()
}
})
.then(function(myJson) {
mod_this.setState({
aircraft: myJson,
loading: false
})
})
}
DisplayAircraft() {
let ac = this.state.aircraft
this.props.clk(ac.data[0].ident)
return (
<div className="acD posRel hidO selected">
{
<h2>{ac.data[0].ident}</h2>
}
</div>
)
}
render() {
const {aircraft} = this.state
return (
<div className="posRel hidO leftD">
<h1>Aircrafts</h1>
{
!aircraft || aircraft.length <= 0 || this.state.loading ?
<Loading /> :
this.DisplayAircraft()
}
</div>
)
}
}
export default Aircraft
When I run my app, I get setState loop error:
Unhandled Rejection (Invariant Violation): Maximum update depth
exceeded. This can happen when a component repeatedly calls setState
inside componentWillUpdate or componentDidUpdate. React limits the
number of nested updates to prevent infinite loops.
The reason I am doing it like this is the Aircraft component will get the Aircraft ID which I want to send to another child component, hence I am sending it to the parent to use it as props for another component.
Section is:
Layout.WhatIsAircraftName [as clk]
The problem is that your render method is not pure and is updating state.
The render() function should be pure, meaning that it does not modify component state, it returns the same result each time it’s invoked, and it does not directly interact with the browser. - React Docs
In your parent component, you have WhatIsAircraftName which is calling setState. Whenever this method is invoked, it will trigger a state update which will trigger a render. In the parent's render you are passing the Aircraft component the prop clk which is assigned to WhatIsAircraftName. Then, in Aircraft's render, it's calling DisplayAircraft, which is invoking the prop clk which starts us back at the top.
Layout#render -> Aircraft#render -> DisplayAircraft -> this.props.clk -> WhatIsAircraftName -> this.setState -> Layout#render -> etc. (infinite loop).
This loop needs to be broken, setState should never be invoked within render.
Try something like this, I've moved the logic around that you are no longer updating the state from the render function.
import React, {Component} from "react"
import Loading from "./Loading"
class Aircraft extends Component {
constructor(props) {
super(props)
this.state = {
aircraft: [],
loading: false,
utilized: 0
}
}
componentDidMount() {
let mod_this = this
this.setState({
loading: true
})
fetch("https://some-endpoint")
.then(function(response) {
if (response.ok) {
return response.json()
}
})
.then(function(myJson) {
this.props.clk(myJson.data[0].ident)
mod_this.setState({
aircraft: myJson,
loading: false
})
})
}
render() {
const {aircraft} = this.state
return (
<div className="posRel hidO leftD">
<h1>Aircrafts</h1>
{
!aircraft || aircraft.length <= 0 || this.state.loading ?
<Loading /> :
(<div className="acD posRel hidO selected">
<h2>{aircraft.data[0].ident}</h2>
</div>)
}
</div>
)
}
}
export default Aircraft
This should at least get it working for you but based on what I can see in your code I do have another suggestion. It would be much simpler to do the API call from the Layout component and then pass the aircraft information down to the Aircraft component via Props. In your current code you are having to pass the data back up via a function you passed via a prop which makes it all a little more complicated. React tends to be much easier to work with when you are passing data down the chain.
Hope that helps!
I need to listen to changes in the state, and if I change it, pass it to the props, but when I try to make the setState an infinite loop and an error begins. Is it possible to make a condition so that there is no error or can there be another way to transfer data from the component?
ProfileTag.js
import React, {Component} from 'react';
import classnames from 'classnames';
import './ProfileTag.scss';
import Tag from './Tag';
class ProfileTag extends Component {
state = {
tags: this.props.tags
}
onKeyUp = (e) => {
// Space -> 32 and enter is 13
if (e.which === 32 || e.which === 13) {
let input = e.target.value.trim().split(" ")[0];
if (input.length === 0 || input[0] === "") return; // empty tags
this.setState({
tags: [...this.state.tags, input]
});
e.target.value = "";
}
}
onDeleteTag = (tag) => {
const tags = this.state.tags.filter((t) => {
return (t !== tag);
});
// console.log("tags: ", tags);
this.setState({tags: tags});
}
componentWillUpdate(nextProps, nextState) {
console.log(nextProps)
console.log(nextState)
this.props.getTags(nextState.tags);
}
render() {
const tags = this.state.tags.map((tag, i) => {
return <Tag
onDeleteTag={this.onDeleteTag}
key={i}
value={tag}/>
});
return (
<div className="ProfileTag">
<label className="ProfileTag__title"
htmlFor={this.props.name}>{this.props.label}</label>
<input
onKeyUp={(e) => this.onKeyUp(e)}
type={this.props.type}
className={classnames('ProfileTag__input')}
placeholder={this.props.placeholder}
name={this.props.name}
id={this.props.name}
value={this.props.value}
disabled={this.props.disabled}
/>
<ul className="ProfileTag__tags">{tags}</ul>
</div>
)
}
}
export default ProfileTag;
Here error:
import React, {Component, Fragment} from 'react';
import connect from 'react-redux/es/connect/connect';
import ProfileTag from '../common/Tag/ProfileTag';
class Profile extends Component {
constructor() {
super();
this.state = {};
}
getTags(tags) {
console.log(tags)
// Here error
this.setState({tata: 'vava'});
}
render() {
let profileContent = (
<div className="Profile">
<ProfileTag
label="Введите теги (ваша основная специальность)"
placeholder="Тег"
name="test1"
tags={this.state.profile.tags}
getTags={this.getTags.bind(this)}
/>
</div>
);
return (
<Fragment>
{profileContent}
</Fragment>
);
}
}
const mapStateToProps = state => ({
profile: state.profile
});
export default connect(mapStateToProps, {getCurrentProfile, postProfile})(Profile);
Two things you should change
componentWillUpdate is deprecated in latest versions, use componentDidUpdate instead
Do not call a function from componentDidUpdate which calls setState directly otherwise your code will go into an infinite loop
Code example
componentDidUpdate(prevProps, prevState) {
if(prevState.tags !== this.state.tags) { // you can use isEqual from lodash for a equality check on arrays or objects
this.props.getTags(this.state.tags);
}
}
in componentDidUpdate ,never use setState,every time when it changes state which would be continuous ,it will go in infinite loop. You can check the with prevprops in componentDidUpdate(object prevProps, object prevState), and make sure you have new props in your hand.
Outside of your componentdidupdate ,create a callback function and with prevprops you can setstate there.
I'm trying to create an infinite siema carousel using algolia's instantsearch in react, but I don't think the connectors behave like React components. Should I expect componentDidMount to be called here? Suggestions? Ideas?
class ActorsClass extends connectStateResults {
constructor(props){
super(props);
var { searchState, searchResults } = props;
this.hasResults = searchResults && searchResults.nbHits !== 0;
}
componentDidMount() {
console.log("componentDidMount " + this.props.siema)
this.siema = new Siema(this.props.siema);
}
prev = () => {
this.siema.prev()
};
next = () => {
this.siema.next()
};
render = () => {
return (
<div className="actors-container">
<div xhidden={!this.hasResults}>
<h1>Actors</h1>
<InfiniteHits hitComponent={HitActors} />
</div>
<button onClick={this.prev}>Prev</button>
<button onClick={this.next}>Next</button>
</div>
);
}
Whenever the connected component receives new props they are re-invoked. It means you can use componentDidUpdate hook for your use case.
You may be interested to use reselect. See the docs for using selector.