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Possible Plagiarism

Plagiarized on 2020-10-28
by abranhe

Original Post

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



            
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This is quite tricky but you can do something like this:
> btw, I am ignoring `onChange` events for the demo.
```js const handleSubmit = e => { e.preventDefault(); const inputs = Object.values(e.target) .filter(c => typeof c.tagName === 'string' && c.tagName.toLowerCase() === 'input') .reduce((acc, curr) => ({ ...acc, [curr.name]: curr.value }), {});
setFormVals({ ...formVals, ...inputs }); } ```
See the demo below:
<!-- begin snippet: js hide: true console: true babel: true -->
<!-- language: lang-js -->
const Demo = () => { const [formValues] = React.useState({});
const handleSubmit = e => { e.preventDefault(); const inputs = Object.values(e.target) .filter(c => typeof c.tagName === 'string' && c.tagName.toLowerCase() === 'input') .reduce((acc, curr) => ({ ...acc, [curr.name]: curr.value }), {});
console.log(inputs); }
return ( <form onSubmit={handleSubmit}> <input name="name" value={formValues.name} /> <input name="email" value={formValues.email} /> <input name="hiddenInput" value="hiddenValue" type="hidden" /> <button type="submit">Submit</button> </form> ); }
ReactDOM.render(<Demo />, document.getElementById('demo'));
<!-- language: lang-html -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.0/umd/react.production.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.0/umd/react-dom.production.min.js"></script>
<div id="demo"></div>
<!-- end snippet -->

That's [*property spread notation*][1]. It was added in ES2018 (spread for arrays/iterables was earlier, ES2015), but it's been supported in React projects for a long time via transpilation (as "[JSX spread attributes][2]" even though you could do it elsewhere, too, not just attributes).
`{...this.props}` *spreads out* the "own" enumerable 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://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax [2]: https://reactjs.org/docs/jsx-in-depth.html#spread-attributes

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