44 lines
1.3 KiB
Markdown
44 lines
1.3 KiB
Markdown
---
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title: LimitedTextarea
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tags: input,state,effect,event,beginner
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---
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Renders a textarea component with a character limit.
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- Use the `React.useState()` hook to create the `content` state variable and set its value to `value`.
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Create a method `setFormattedContent`, which trims the content of the input if it's longer than `limit`.
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- Use the `React.useEffect()` hook to call the `setFormattedContent` method on the value of the `content` state variable.
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- Use a`<div>` to wrap both the`<textarea>` and the `<p>` element that displays the character count and bind the `onChange` event of the `<textarea>` to call `setFormattedContent` with the value of `event.target.value`.
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```jsx
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function LimitedTextarea({ rows, cols, value, limit }) {
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const [content, setContent] = React.useState(value);
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const setFormattedContent = text => {
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text.length > limit ? setContent(text.slice(0, limit)) : setContent(text);
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};
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React.useEffect(() => {
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setFormattedContent(content);
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}, []);
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return (
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<div>
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<textarea
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rows={rows}
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cols={cols}
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onChange={event => setFormattedContent(event.target.value)}
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value={content}
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/>
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<p>
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{content.length}/{limit}
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</p>
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</div>
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);
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}
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```
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```jsx
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ReactDOM.render(<LimitedTextarea limit={32} value="Hello!" />, document.getElementById('root'));
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```
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