change limited text area component to hooks implementation

This commit is contained in:
komv8i
2019-02-07 11:22:58 -05:00
parent 509f7e87fa
commit 125e61fead

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@ -2,41 +2,41 @@
Renders a textarea component with a character limit. Renders a textarea component with a character limit.
Use the value of the `value` prop to determine the initial `state.content` and `state.characterCount` and the value of the `limit` props to determine the value of `state.limit`. Use the `value` and `limit` props to pass in the initial `content` and the `limit` values for the LimitedTextArea component.
Create a method, `handleChange`, which trims the `event.target.value` data if necessary and uses `Component.prototype.setState` to update `state.content` and `state.characterCount`, and bind it to the component's context. Create a method, `handleChange`, which trims the `event.target.value` data if necessary and updates `content` with the new entered content.
In the`render()` method, 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 the `handleChange` method. In the`render()` method, 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 the `handleChange` method.
```jsx ```jsx
class LimitedTextarea extends React.Component { function LimitedTextArea(props) {
constructor(props) { const { rows, cols, value, limit } = props;
super(props);
this.state = { const setFormattedContent = text => {
content: props.value, text.length > limit ? setContent(text.slice(0, limit)) : setContent(text);
characterCount: props.value.length, };
limit: props.limit
}; const [content, setContent] = useState(value);
this.handleChange = this.handleChange.bind(this); // Run once to test if the initial value is greater than the limit
} useEffect(() => {
setFormattedContent(content);
}, []);
const handleChange = event => {
setFormattedContent(event.target.value);
};
handleChange(event) {
let newContent = event.target.value;
if(newContent.length >= this.state.limit) newContent = newContent.slice(0, this.state.limit);
this.setState(state => ({ content: newContent, characterCount: newContent.length }));
}
render() {
return ( return (
<div> <div>
<textarea <textarea
rows={this.props.rows} rows={rows}
cols={this.props.cols} cols={cols}
onChange={this.handleChange} onChange={handleChange}
value={this.state.content} value={content}
> />
</textarea> <p>
<p>{this.state.characterCount}/{this.props.limit}</p> {content.length}/{limit}
</p>
</div> </div>
); );
}
} }
``` ```
@ -46,7 +46,6 @@ ReactDOM.render(
document.getElementById('root') document.getElementById('root')
); );
``` ```
<!-- tags: input,state,class --> <!-- tags: input,state,class -->
<!-- expertise: 0 --> <!-- expertise: 0 -->