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Inside React: Then and Now Tianyu (Tian) Pu

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No content

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Back to the basics

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Click me!

{text}

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Click me!

{text}

const sillyDiv = ({ text }) => ( )

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Click me!

{text}

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Click me!

{text}

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Click me!

{text}

class SillyDiv extends React.Component { }

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Click me!

{text}

class SillyDiv extends React.Component { render() { return ( ) } }

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Click me!

{this.props.text}

class SillyDiv extends React.Component { render() { return ( ) } }

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Click me!

{this.props.text}

class SillyDiv extends React.Component { render() { return ( ) } }

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Click me!

{this.props.text}

class SillyDiv extends React.Component { render() { return ( ...

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Click me!

{this.props.text}

class SillyDiv extends React.Component { render() { return ( ...

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this.setState({ })} >Click me!

{this.props.text}

class SillyDiv extends React.Component { render() { return ( ...

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this.setState({ text: new Date().toString() })} >Click me!

{this.props.text}

class SillyDiv extends React.Component { render() { return ( ...

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this.setState({ text: new Date().toString() })} >Click me!

{this.props.text}

class SillyDiv extends React.Component { render() { return ( ...

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this.setState({ text: new Date().toString() })} >Click me!

{this.state.text}

class SillyDiv extends React.Component { render() { return ( ...

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this.setState({ text: new Date().toString() })} >Click me!

{this.state.text}

class SillyDiv extends React.Component { render() { return (

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, document.getElementById('root')

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ReactDOM.render( , document.getElementById('root') );

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“Tell me what you want to see,

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“Tell me what you want to see, and I’ll make it happen.”

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Reconciliation

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Rendering

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Before React 16

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ReactDOM.render( , document.getElementById('root') );

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ReactDOM.render( , document.getElementById('root') );

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Click me!

{this.state.text}

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Components: host vs composite

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ReactDOM.render( , document.getElementById('root') );

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Click me!

{this.state.text}

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function mount(component) { }

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function mount(component) { if (host component) // create DOM node // mount children }

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function mount(component) { if (host component) // create DOM node // mount children if (composite component) // call render() of component // mount the result of render() }

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What happens if I call ReactDOM.render() again?

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SillyDiv

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div button p SillyDiv

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div button p SillyDiv mount() mount() mount() mount()

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class DOMComponent { } class CompositeComponent { }

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class DOMComponent { mount() } class CompositeComponent { mount() }

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class DOMComponent { currentElement mount() } class CompositeComponent { currentElement mount() }

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class DOMComponent { currentElement renderedChildren mount() } class CompositeComponent { currentElement renderedElement mount() }

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class DOMComponent { currentElement renderedChildren node mount() } class CompositeComponent { currentElement renderedElement publicInstance mount() }

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A word about terminology...

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class DOMComponent { currentElement renderedChildren node mount() } class CompositeComponent { currentElement renderedElement publicInstance mount() }

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So, what about updates?

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class DOMComponent { currentElement renderedChildren node mount() } class CompositeComponent { currentElement renderedElement publicInstance mount() }

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class DOMComponent { currentElement renderedChildren node mount() receive(nextEl) } class CompositeComponent { currentElement renderedElement publicInstance mount() receive(nextEl) }

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function receive(nextEl) { }

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function receive(nextEl) { // figure out next rendered element // if same type, call receive() // otherwise, make changes }

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function receive(nextEl) { // figure out next rendered element // if same type, call receive() // otherwise, make changes }

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function receive(nextEl) { // figure out next rendered element // if same type, call receive() // otherwise, make changes }

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What could possibly go wrong?

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div button p SillyDiv

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div button p SillyDiv Box ... ... ...

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The JS event loop

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render paint process messages

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render paint process messages div button p SillyDiv

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render paint process messages ... ... ...

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render paint process messages ... ... ...

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What have we learned about React <16?

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React 16: “Fiber”

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isfiberreadyyet.com

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Core idea: Separate renconciliation from rendering

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“Render” vs “commit” phases

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What is a fiber?

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{ }

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{ stateNode }

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{ stateNode child }

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{ stateNode child sibling }

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{ stateNode child sibling return }

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Representing components with fibers

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div button p SillyDiv

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div button p SillyDiv CompositeComponent DOMComponent

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div button p SillyDiv fiber fiber fiber fiber

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div button p SillyDiv child

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div button p SillyDiv child return

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div button p SillyDiv child return child

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div button p SillyDiv child return child sibling

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div button p SillyDiv child return child sibling return return

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Life of an update

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div button p SillyDiv

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div button p SillyDiv setState()

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div button p SillyDiv updateQueue

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div button p SillyDiv updateQueue scheduleWork()

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requestIdleCallback

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv

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div button p SillyDiv workInProgress

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div button p SillyDiv div button p SillyDiv workInProgress current

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div button p SillyDiv div button p SillyDiv current workInProgress

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Great, but so what?

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div button p SillyDiv workInProgress

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div button p SillyDiv workInProgress

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div button p SillyDiv workInProgress

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div button p SillyDiv workInProgress

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div button p SillyDiv New work arrives workInProgress

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div button p SillyDiv Example 1: High priority update workInProgress

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div button p SillyDiv workInProgress updateQueue

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div button p SillyDiv workInProgress updateQueue scheduleWork()

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div button p SillyDiv Example 2: Animation update workInProgress

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How far we’ve come

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Thank you! https://linkedin.com/in/tianyupu https://speakerdeck.com/tianyupu/ inside-react-then-and-now

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Credits https://github.com/acdlite/react-fiber-architecture https://www.youtube.com/watch?v=ZCuYPiUIONs