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Q&A Are there other reasons why useEffect might not be defined apart from not importing it?

I am creating a button that once clicked will change from off to on with react and i am also creating a responsive clock through useEffect. Yet the code still return that useEffect is undefined th...

2 answers · posted 1y ago by Brian‭ · last activity 1y ago by jmathew‭

Question reactjs react-hooks

#4: Post edited by

Alexei‭ · 2023-05-25T06:08:48Z (over 1 year ago)
added related tag

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reactjs

reactjs react-hooks

#3: Post edited by

trichoplax‭ · 2023-05-25T05:05:27Z (over 1 year ago)
Fix backticks so syntax highlighting will work, fix typo in title

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~~Are there other reasons why useEfffect might not be defined apart from not importing it?~~

Are there other reasons why useEffect might not be defined apart from not importing it?

I am creating a button that once clicked will change from off to on with react and i am also creating a responsive clock through useEffect.
Yet the code still return that useEffect is undefined though i imported useState.
~~``````import {useState} from 'react';~~
import "./styles.css";
export default function App() {
let [PresentState, setPresentState] = useState(false);
let [time, seTime] = useState("00:00:00");
function toggleState() {
setPresentState((prevState) => !prevState);
}
function getTime() {
return new Date().getTime();
}
useEffect(() => {
setTime(getTime());
console.log();
return () => {};
},[]);
return (
<div className="app">
<button onClick={toggleState} className="btn">
{PresentState ? "On" : "Off"}
</button>
<time>00:00:00</time>
</div>
);
}
``````

I am creating a button that once clicked will change from off to on with react and i am also creating a responsive clock through useEffect.
Yet the code still return that useEffect is undefined though i imported useState.
```
import {useState} from 'react';
import "./styles.css";
export default function App() {
let [PresentState, setPresentState] = useState(false);
let [time, seTime] = useState("00:00:00");
function toggleState() {
setPresentState((prevState) => !prevState);
}
function getTime() {
return new Date().getTime();
}
useEffect(() => {
setTime(getTime());
console.log();
return () => {};
},[]);
return (
<div className="app">
<button onClick={toggleState} className="btn">
{PresentState ? "On" : "Off"}
</button>
<time>00:00:00</time>
</div>
);
}
```

#2: Post edited by

Brian‭ · 2023-05-24T06:23:52Z (over 1 year ago)

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I am creating a button that once clicked will change from off to on with react and i am also creating a responsive clock through useEffect.
Yet the code still return that useEffect is undefined though i imported useState.
~~`import {useState} from 'react';~~
import "./styles.css";
export default function App() {
let [PresentState, setPresentState] = useState(false);
let [time, seTime] = useState("00:00:00");
function toggleState() {
setPresentState((prevState) => !prevState);
}
function getTime() {
return new Date().getTime();
}
useEffect(() => {
setTime(getTime());
console.log();
return () => {};
},[]);
return (
<div className="app">
<button onClick={toggleState} className="btn">
{PresentState ? "On" : "Off"}
</button>
<time>00:00:00</time>
</div>
);
}
`

I am creating a button that once clicked will change from off to on with react and i am also creating a responsive clock through useEffect.
Yet the code still return that useEffect is undefined though i imported useState.
``````import {useState} from 'react';
import "./styles.css";
export default function App() {
let [PresentState, setPresentState] = useState(false);
let [time, seTime] = useState("00:00:00");
function toggleState() {
setPresentState((prevState) => !prevState);
}
function getTime() {
return new Date().getTime();
}
useEffect(() => {
setTime(getTime());
console.log();
return () => {};
},[]);
return (
<div className="app">
<button onClick={toggleState} className="btn">
{PresentState ? "On" : "Off"}
</button>
<time>00:00:00</time>
</div>
);
}
``````

#1: Initial revision by

Brian‭ · 2023-05-24T06:22:50Z (over 1 year ago)

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Are there other reasons why useEfffect might not be defined apart from not importing it?

I am creating a button that once clicked will change from off to on with react and i am also creating a responsive clock through useEffect.

Yet the code still return that useEffect is undefined though i imported useState.

`import {useState} from 'react';
import "./styles.css";
export default function App() {
  let [PresentState, setPresentState] = useState(false);
  let [time, seTime] = useState("00:00:00");
  function toggleState() {
    setPresentState((prevState) => !prevState);
  }
  function getTime() {
    return new Date().getTime();
  }

  useEffect(() => {
    setTime(getTime());
    console.log();
    return () => {};
  },[]);
  return (
    <div className="app">
      <button onClick={toggleState} className="btn">
        {PresentState ? "On" : "Off"}
      </button>
      <time>00:00:00</time>
    </div>
  );
}

`

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