Commit 171b61b

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clean up function doesn't only run when compnent unmounts

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+14

-10

lines changed

+14

-10

lines changed

Lines changed: 2 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -2,9 +2,9 @@ import React from 'react';`
`2`	`2`	`import ReactDOM from 'react-dom';`
`3`	`3`
`4`	`4`	`// import App from './useState-example';`
`5`		`-// import App from './useEffect-example';`
	`5`	`+import App from './useEffect-example';`
`6`	`6`	`// import App from './customHook-example';`
`7`		`-import App from './useDataApiHook-example';`
	`7`	`+// import App from './useDataApiHook-example';`
`8`	`8`
`9`	`9`	`import * as serviceWorker from './serviceWorker';`
`10`	`10`

Lines changed: 12 additions & 8 deletions

Original file line number	Diff line number	Diff line change
`@@ -4,14 +4,18 @@ function App() {`
`4`	`4`	`const [isOn, setIsOn] = useState(false);`
`5`	`5`	`const [timer, setTimer] = useState(0);`
`6`	`6`
`7`		`- useEffect(() => {`
`8`		`- const interval = setInterval(`
`9`		`- () => isOn && setTimer(timer + 1),`
`10`		`- 1000,`
`11`		`- );`
`12`		`-`
`13`		`- return () => clearInterval(interval);`
`14`		`- }, []);`
	`7`	`+ useEffect(`
	`8`	`+ () => {`
	`9`	`+ let interval;`
	`10`	`+`
	`11`	`+ if (isOn) {`
	`12`	`+ interval = setInterval(() => setTimer(timer + 1), 1000);`
	`13`	`+ }`
	`14`	`+`
	`15`	`+ return () => clearInterval(interval);`
	`16`	`+ },`
	`17`	`+ [isOn],`
	`18`	`+ );`
`15`	`19`
`16`	`20`	`const onReset = () => {`
`17`	`21`	`setIsOn(false);`

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