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setState using its callback inside useEffect causing infinite looping

I know this is an over asked question regarding useEffect and useState infinite loops. I have read almost every question about it and also searched over the internet in order to try to fix it before posting here. The most recent article that I read was this one.
Before I read the article my useState function inside useEffect was without the useState's callback, so it was what I thought which was causing the problem. But after moving it from this:
setNotifications({
...notifications,
[type]: {
...notifications[type],
active: portfolioSettings[type],
payload: {
...notifications[type].payload,
[pKey]: portfolioSettings[pKey],
},
},
});
to this:
setNotifications((currState) => ({
...currState,
[type]: {
...currState[type],
active: portfolioSettings[type],
payload: {
...currState[type].payload,
[pKey]: portfolioSettings[pKey],
},
},
}));
Unfortunately the infinite loop persists. Here are all useEffect functions (the last one is the one causing the infinite looping) that I'm using in this component.
// Set default selected portfolio to the active portfolio
useEffect(() => {
let mounted = true;
const setPortfolioData = () => {
if (activePortfolio) {
const portfolioId = activePortfolio.id;
const portfolioName = activePortfolio.name;
setSelectedPortfolio({
portfolioId,
portfolioName,
});
}
};
if (mounted) setPortfolioData();
return () => {
mounted = false;
};
}, [activePortfolio]);
// Set all the categories if no category is set
useEffect(() => {
let mounted = true;
if (mounted && allCvmCategories) {
const allCvmCategoriesNames = allCvmCategories.map((c) => c);
setNotifications((currState) => ({
...currState,
isCvmNotificationEnabled: {
...currState.isCvmNotificationEnabled,
payload: {
...currState.isCvmNotificationEnabled.payload,
cvmCategories: allCvmCategoriesNames,
},
},
}));
setIsCvmCategoriesReady(true);
}
return () => {
mounted = false;
};
}, [allCvmCategories]);
// THE ONE WHICH IS CAUSING INFINITE LOOPING
// THE notificationsTypes AND notificationsInitialState
// ARE DECLARED IN THE ROOT OF THE JSX FILE
// OUT OF THE FUNCTIONAL COMPONENT
useEffect(() => {
let mounted = true;
if (
mounted &&
isCvmCategoriesReady &&
allPortfolios &&
selectedPortfolio.portfolioId
) {
const { portfolioId } = selectedPortfolio;
const portfolioSettings = allPortfolios[portfolioId].settings;
if (portfolioSettings) {
notificationsTypes.forEach((type) => {
if (Object.prototype.hasOwnProperty.call(portfolioSettings, type)) {
const { payloadKeys } = notificationsInitialState[type];
if (payloadKeys.length > 0) {
payloadKeys.forEach((pKey) => {
if (
Object.prototype.hasOwnProperty.call(portfolioSettings, pKey)
) {
setNotifications((currState) => ({
...currState,
[type]: {
...currState[type],
active: portfolioSettings[type],
payload: {
...currState[type].payload,
[pKey]: portfolioSettings[pKey],
},
},
}));
}
});
} else {
setNotifications((currState) => ({
...currState,
[type]: {
...currState[type],
active: portfolioSettings[type],
},
}));
}
}
});
}
}
return () => {
mounted = false;
};
}, [allPortfolios, isCvmCategoriesReady, selectedPortfolio]);

Thanks for the responses. I have found the problem, it was with the hook that I was using (SWR) for fetching. Making the allPortfolios change all the time. I have fixed it wrapping into a new custom hook.

I have a stopwatch in reactjs, how can I add each number into some sort of array to show each number?

I created a stopwatch using react. My stopwatch starts from 0 and stops at the press of the space button with componenDidMount and componentWillMount. My issue is, I can't seem to figure out how to create some sort of list with the numbers the stopwatch returns. I've created:
times = () => {
this.setState(previousState => ({
myArray: [...previousState.myArray, this.state.milliSecondsElapsed]
}));
};
and then in render() to print it.
<h1>{this.times}</h1>
What I'm trying to do is to create some sort of array that'll keep track of milliSecondsElapsed in my handleStart and handleStop method.
Here's what I have.
import React, {Component} from "react";
import Layout from '../components/MyLayout.js';
export default class Timer extends React.Component {
constructor(props) {
super(props);
this.state = {
milliSecondsElapsed: 0,
timerInProgress: false // state to detect whether timer has started
};
this.updateState = this.updateState.bind(this);
this.textInput = React.createRef();
}
componentDidMount() {
window.addEventListener("keypress", this.keyPress);
}
componentWillUnmount() {
window.removeEventListener("keypress", this.keyPress);
}
textInput = () => {
clearInterval(this.timer);
};
updateState(e) {
this.setState({})
this.setState({ milliSecondsElapsed: e.target.milliSecondsElapsed });
}
keyPress = (e) => {
if (e.keyCode === 32) {
// some logic to assess stop/start of timer
if (this.state.milliSecondsElapsed === 0) {
this.startBtn.click();
} else if (this.state.timerInProgress === false) {
this.startBtn.click();
} else {
this.stopBtn.click();
}
}
};
handleStart = () => {
if (this.state.timerInProgress === true) return;
this.setState({
milliSecondsElapsed: 0
});
this.timer = setInterval(() => {
this.setState(
{
milliSecondsElapsed: this.state.milliSecondsElapsed + 1,
timerInProgress: true
},
() => {
this.stopBtn.focus();
}
);
}, 10);
};
handleStop = () => {
this.setState(
{
timerInProgress: false
},
() => {
clearInterval(this.timer);
this.startBtn.focus();
}
);
};
times = () => {
this.setState(previousState => ({
myArray: [...previousState.myArray, this.state.milliSecondsElapsed]
}));
};
render() {
return (
<Layout>
<div className="index" align='center'>
<input
value={this.state.milliSecondsElapsed/100}
onChange={this.updateState}
ref={this.textInput}
readOnly={true}
/>
<button onClick={this.handleStart} ref={(ref) => (this.startBtn = ref)}>
START
</button>
<button onClick={this.handleStop} ref={(ref) => (this.stopBtn = ref)}>
STOP
</button>
<h1>{this.state.milliSecondsElapsed/100}</h1>
</div>
</Layout>
);
}
}

Issue
this.times is a function that only updates state, it doesn't return any renderable JSX.
times = () => {
this.setState((previousState) => ({
myArray: [...previousState.myArray, this.state.milliSecondsElapsed]
}));
};
Solution
Create a myArray state.
this.state = {
myArray: [], // <-- add initial empty array
milliSecondsElapsed: 0,
timerInProgress: false // state to detect whether timer has started
};
Move the state update logic from this.times to this.handleStop.
handleStop = () => {
this.setState(
(previousState) => ({
timerInProgress: false,
myArray: [
...previousState.myArray, // <-- shallow copy existing data
this.state.milliSecondsElapsed / 100 // <-- add new time
]
}),
() => {
clearInterval(this.timer);
this.startBtn.focus();
}
);
};
Render the array of elapsed times as a comma separated list.
<div>{this.state.myArray.join(", ")}</div>
Full code
class Timer extends React.Component {
constructor(props) {
super(props);
this.state = {
myArray: [],
milliSecondsElapsed: 0,
timerInProgress: false // state to detect whether timer has started
};
this.updateState = this.updateState.bind(this);
this.textInput = React.createRef();
}
componentDidMount() {
window.addEventListener("keypress", this.keyPress);
}
componentWillUnmount() {
window.removeEventListener("keypress", this.keyPress);
}
textInput = () => {
clearInterval(this.timer);
};
updateState(e) {
this.setState({ milliSecondsElapsed: e.target.milliSecondsElapsed });
}
keyPress = (e) => {
if (e.keyCode === 32) {
// some logic to assess stop/start of timer
if (this.state.milliSecondsElapsed === 0) {
this.startBtn.click();
} else if (this.state.timerInProgress === false) {
this.startBtn.click();
} else {
this.stopBtn.click();
}
}
};
handleStart = () => {
if (this.state.timerInProgress === true) return;
this.setState({
milliSecondsElapsed: 0
});
this.timer = setInterval(() => {
this.setState(
{
milliSecondsElapsed: this.state.milliSecondsElapsed + 1,
timerInProgress: true
},
() => {
this.stopBtn.focus();
}
);
}, 10);
};
handleStop = () => {
this.setState(
(previousState) => ({
timerInProgress: false,
myArray: [
...previousState.myArray,
this.state.milliSecondsElapsed / 100
]
}),
() => {
clearInterval(this.timer);
this.startBtn.focus();
}
);
};
render() {
return (
<div>
<div className="index" align="center">
<input
value={this.state.milliSecondsElapsed / 100}
onChange={this.updateState}
ref={this.textInput}
readOnly={true}
/>
<button
onClick={this.handleStart}
ref={(ref) => (this.startBtn = ref)}
>
START
</button>
<button onClick={this.handleStop} ref={(ref) => (this.stopBtn = ref)}>
STOP
</button>
<h1>{this.state.milliSecondsElapsed / 100}</h1>
</div>
<div>{this.state.myArray.join(", ")}</div>
</div>
);
}
}

React setTimeout hooks onclick

It is giving an error Cannot read property 'handleCheck' of undefined when I click on next button. Can anyone please help?Thanks in advance
import React from "react";
import ReactDOM from "react-dom";
class App extends React.Component {
state = { check: false };
handleCheck = () => {
console.log("hello");
this.setState({ check: !this.state.check });
};
componentDidMount() {
setTimeout(() => {
this.handleCheck();
}, 10000);
}
timer() {
setTimeout(() => {
this.handleCheck();
}, 10000);
}
render() {
return (
<div>
<p>hello</p>
{this.state.check ? (
<button onClick={this.timer}>Next</button>
) : (
<div>button not showing </div>
)}
</div>
);
}
}
ReactDOM.render(<App />, document.getElementById("container"));

The timer should also be an arrow function to refer to the correct this:
timer = () => {
setTimeout(() => {
this.handleCheck();
}, 10000);
}
the other way to fix this would be to bind this to timer.
And since the new state depends on the old state, the handleCheck function should be like this:
handleCheck = () => {
console.log("hello");
this.setState(prevState => ({ check: !prevState.check }));
};

make it an arrow function:
timer = () => {
setTimeout(() => {
this.handleCheck();
}, 1000);
}
so it's bound to the parent scope

It's a binding issue of timer function :
timer = () => {
setTimeout(() => {
this.handleCheck();
}, 10000);
}
OR change onClick :
onClick={this.timer.bind(this)}
Solution :
class App extends React.Component {
state = { check: false };
handleCheck = () => {
console.log("hello");
this.setState({ check: !this.state.check });
};
componentDidMount() {
setTimeout(() => {
this.handleCheck();
}, 10000);
}
timer = () => {
setTimeout(() => {
this.handleCheck();
}, 10000);
}
render() {
return (
<div>
<p>hello</p>
{this.state.check ? (
<button onClick={this.timer}>Next</button>
) : (
<div>button not showing </div>
)}
</div>
);
}
}
ReactDOM.render(<App />, document.getElementById("react-root"));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.19.2/axios.min.js"></script>
<div id="react-root"></div>

You need to bind this to the timer function.
<button onClick={this.timer.bind(this)}>Next</button>

You can use the arrow function as other users said, or as alternative you can manually bind this to the function:
// in the button
<button onClick={this.timer.bind(this)}>Next</button>
// or in the constructor
constructor(props) {
super(props)
this.timer = this.timer.bind(this)
}
<button onClick={this.timer)}>Next</button>

hi as previous people said you need to bind (this) one of the way is to do it like this
class App extends React.Component {
constructor(props) {
super(props);
this.state = { check: false };
// This binding is necessary to make `this` work in the callback
this.handleCheck = this.handleCheck.bind(this);
}
this is happens because when you enter a function the class this can't be reach
bind solve this in regular function
when you go with arrow function this scope don't use there on this scope instead they inherit the one from the parent scope
like this:
instead of:
timer() {
setTimeout(() => {
this.handleCheck();
}, 10000);
}
do this:
timer = () => {
setTimeout(() => {
this.handleCheck();
}, 10000);
}

'x' refresh is not a function. (In 'x()', 'x' is an instance of Object)

How can I access to my refresh() method in my UpdateLokalListe function?
Is there any possibility to include the function in my class?
I used this guide: https://reactnavigation.org/docs/function-after-focusing-screen
Thanks
https://pastebin.com/NMfTS8tp
function UpdateLokalListe(refresh) {
useFocusEffect(
React.useCallback(() => {
refresh();
})
);
return null;
}
export default class LokaleBearbeitenScreen extends Component {
state = {
lokale: [],
isLoading: true,
};
_retrieveData = async () => {
...
};
_refresh = () => {
alert('refresh');
this.setState({ isLoading: true });
this._retrieveData();
};
componentDidMount() {
Firebase.init();
this._retrieveData();
}
render() {
...
return (
<>
<UpdateLokalListe refresh={this._refresh} />
...
</>
);
}
}

UpdateLokalListe looks like functional component, and you are passing refresh props
So change this :
UpdateLokalListe(refresh)
to :
UpdateLokalListe({refresh})
OR
function UpdateLokalListe(props) { // <---- Here
useFocusEffect(
React.useCallback(() => {
props.refresh(); // <---- Here
})
);
return null;
}

setState(…): Can only update a mounted or mounting component

This is the code. No idea as to why there is a problem.
class TeacherForm extends Component {
constructor({ data }) {
super();
this.isUpdatingForm = !! data;
this.state = Object.assign({ ... });
this.handleSubmit = this.handleSubmit.bind(this);
this.removeTeacher = this.removeTeacher.bind(this);
}
handleChange(value, field) {
this.setState({ shouldUpdate: true, [field]: value });
}
handleSubmit(e) {
e.preventDefault();
const { name, subjects, parttime, timing } = this.state;
if (this.isUpdatingForm) {
return update.call({
_id: this.props.data._id,
transaction: { name, subjects, parttime, timing },
}, () => this.setState({ shouldUpdate: false }));
}
return add.call();
}
removeTeacher() {
return remove.call(this.props.data._id);
}
render() {
return (
<form onSubmit={this.handleSubmit}>
...
</form>
);
}
}
The error gets thrown at the handleSubmit method in the callback of update.call. This normally shows up when I call removeTeacher and a list updates and this component unmounts.

It sounds like the callback () => this.setState({ shouldUpdate: false }) is executed after that the component is unmounted. Is that possible? If so, one way to get around that is to replace this part by
return update.call({
_id: this.props.data._id,
transaction: { name, subjects, parttime, timing },
}, () => { !this.unmounted && this.setState({ shouldUpdate: false }); });
and to add
componentWillUnmount() {
this.unmounted = true;
}