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14-references.html
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14-references.html
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<!doctype html>
<title>14 References - React From Zero</title>
<script src="https://unpkg.com/[email protected]/dist/react.js"></script>
<script src="https://unpkg.com/[email protected]/dist/react-dom.js"></script>
<script src="https://unpkg.com/[email protected]/browser.min.js"></script>
<div id="app"></div>
<script type="text/babel">
// Sometimes we need some state from an element or a component
// or it has to be directly modified somehow. For
// this case, we can tell React to create references.
var RefComponent = React.createClass({
// First we tell React to render an input with a
// ref callback, it will be called, when the DOM of the input element
// is available
render: function() {
return (
<div>
<input ref={this.handleRef}/>
<button onClick={this.handleClick}>Do Something</button>
</div>
)
},
// This callback is called when the input element was mounted into the DOM
// and again, with null, when it was unmounted again
// For elements the rendered DOM node will be stored
// For components the instance of the component will be stored.
handleRef(nameInput) {
// We save a reference to it for later use.
this.nameInput = nameInput
},
// This callback is called when the button is clicked
// and uses this.nameInput to read out the value of the input.
handleClick: function() {
console.log(this.nameInput.value)
},
})
// Since references are local to their component
// they can be used as local IDs to get elements
// and don't override each other when another
// instance of the component is created
var reactElement =
<div>
<RefComponent/>
<RefComponent/>
<RefComponent/>
</div>
ReactDOM.render(reactElement, document.getElementById('app'))
</script>