61 lines
2.0 KiB
Markdown
61 lines
2.0 KiB
Markdown
---
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title: LimitedWordTextarea
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tags: components,input,state,effect,event,beginner
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---
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Renders a textarea component with a word limit.
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- Use the `React.useState()` hook to create the `content` and `wordCount` state variables and set their values to `value` and `0` respectively.
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- Create a method `setFormattedContent`, which uses `String.prototype.split(' ')` to turn the input into an array of words and check if the result of applying `Array.prototype.filter(Boolean)` has a `length` longer than `limit`.
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- If the afforementioned `length` exceeds the `limit`, trim the input, otherwise return the raw input, updating `content` and `wordCount` accordingly in both cases.
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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 LimitedWordTextarea({ rows, cols, value, limit }) {
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const [content, setContent] = React.useState(value);
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const [wordCount, setWordCount] = React.useState(0);
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const setFormattedContent = text => {
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let words = text.split(' ');
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if (words.filter(Boolean).length > limit) {
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setContent(
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text
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.split(' ')
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.slice(0, limit)
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.join(' ')
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);
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setWordCount(limit);
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} else {
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setContent(text);
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setWordCount(words.filter(Boolean).length);
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}
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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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{wordCount}/{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(
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<LimitedWordTextarea limit={5} value="Hello there!" />,
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document.getElementById('root')
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);
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```
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