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Possible Plagiarism

Plagiarized on 2019-04-03
by mthrsj

Original Post

Original - Posted on 2015-06-25
by T.J. Crowder



            
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You could have 2 different handlers for you inputs. On the first, when it is trigerred, it changes the value for the first and for the second input. For the second, it just changes the value for the second. Snippet below:
<!-- begin snippet: js hide: false console: true babel: true -->
<!-- language: lang-js -->
class App extends React.Component { constructor(props){ super(props) this.state = { h5: "", titan: "" } } handleH5Change = (e) => { this.setState({ h5: e.target.value, titan: e.target.value }) } handleTitanChange = (e) => { this.setState({ titan: e.target.value }) } render() { return ( <div> <input value={this.state.h5} onChange={this.handleH5Change} /> <input value={this.state.titan} onChange={this.handleTitanChange} /> </div> ) } }
ReactDOM.render(<App/>, document.getElementById("app"))
<!-- language: lang-html -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="app"></div>
<!-- end snippet -->

That's *property spread notation*. It was added in ES2018, but long-supported in React projects via transpilation (as "JSX spread attributes" even though you could do it elsewhere, too, not just attributes).
`{...this.props}` *spreads out* the "own" properties in `props` as discrete properties on the `Modal` element you're creating. For instance, if `this.props` contained `a: 1` and `b: 2`, then
<Modal {...this.props} title='Modal heading' animation={false}>
would be the same as
<Modal a={this.props.a} b={this.props.b} title='Modal heading' animation={false}>
But it's dynamic, so whatever "own" properties are in `props` are included.
Since `children` is an "own" property in `props`, spread will include it. So if the component where this appears had child elements, they'll be passed on to `Modal`. Putting child elements between the opening tag and closing tags is just syntactic sugar&nbsp;&mdash; the good kind&nbsp;&mdash; for putting a `children` property in the opening tag. Example:
<!-- begin snippet: js hide: true console: true babel: true -->
<!-- language: lang-js -->
class Example extends React.Component { render() { const { className, children } = this.props; return ( <div className={className}> {children} </div> ); } } ReactDOM.render( [ <Example className="first"> <span>Child in first</span> </Example>, <Example className="second" children={<span>Child in second</span>} /> ], document.getElementById("root") );
<!-- language: lang-css -->
.first { color: green; } .second { color: blue; }
<!-- language: lang-html -->
<div id="root"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<!-- end snippet -->
Spread notation is handy not only for that use case, but for creating a new object with most (or all) of the properties of an existing object&nbsp;&mdash; which comes up a lot when you're updating state, since you can't modify state directly:
this.setState(prevState => { return {foo: {...prevState.foo, a: "updated"}}; });
That replaces `this.state.foo` with a new object with all the same properties as `foo` except the `a` property, which becomes `"updated"`:
<!-- begin snippet: js hide: true console: true babel: false -->
<!-- language: lang-js -->
const obj = { foo: { a: 1, b: 2, c: 3 } }; console.log("original", obj.foo); // Creates a NEW object and assigns it to `obj.foo` obj.foo = {...obj.foo, a: "updated"}; console.log("updated", obj.foo);

<!-- language: lang-css -->
.as-console-wrapper { max-height: 100% !important; }
<!-- end snippet -->
[1]: https://reactjs.org/docs/jsx-in-depth.html#children-in-jsx

        
Present in both answers; Present only in the new answer; Present only in the old answer;