31 lines
924 B
Markdown
31 lines
924 B
Markdown
---
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title: useToggler
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tags: hooks,state,callback,beginner
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firstSeen: 2020-11-27T09:41:31+02:00
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lastUpdated: 2020-11-27T09:41:31+02:00
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---
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Provides a boolean state variable that can be toggled between its two states.
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- Use the `useState()` hook to create the `value` state variable and its setter.
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- Create a function that toggles the value of the `value` state variable and memoize it, using the `useCallback()` hook.
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- Return the `value` state variable and the memoized toggler function.
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```jsx
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const useToggler = initialState => {
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const [value, setValue] = React.useState(initialState);
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const toggleValue = React.useCallback(() => setValue(prev => !prev), []);
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return [value, toggleValue];
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};
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```
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```jsx
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const Switch = () => {
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const [val, toggleVal] = useToggler(false);
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return <button onClick={toggleVal}>{val ? 'ON' : 'OFF'}</button>;
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};
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ReactDOM.render(<Switch />, document.getElementById('root'));
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```
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