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React js | PPT
React: A Sneak Peak
Jai Santhosh
UI Engineer @ Flipkart
@jaisanth
Meet React.
Not yet another JS framework!
Meet React.
But just a library for creating user
interfaces.
Meet React.
Renders your UI and responds to
events.
Meet React.
a.k.a. The “V” in

MVC
Build components,
not templates
Build components,
not templates
Re-render, don’t mutate
Build components,
not templates
Re-render, don’t mutate
Fast Virtual DOM
Build components, not templates

• Combine DOM generation and display logic.

9
Build components, not templates

• Combine DOM generation and display logic.

• Transform data into interface components.

10
Build components, not templates

• Combine DOM generation and display logic.

• Transform data into interface components.

• Data can come from anywhere.

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Build components, not templates

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Build components, not templates

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JSX
Allows you to write JS & XML
JSX
Allows you to write JS & XML
Together!
JSX
Don’t need to use it as such
JSX
React.DOM.div({}, 'Hello ' + this.props.name)
Re-render, don’t mutate!

• Every component has “state” and “props”.

18
Re-render, don’t mutate!

• Every component has “state” and “props”.

• Acts as an “Immutable DOM”.

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Re-render, don’t mutate!

• Every component has “state” and “props”.

• Acts as an “Immutable DOM”.

• Re-render the whole app once the state changes.

20
Re-render, don’t mutate!

Data is guaranteed
to update!

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Re-render, don’t mutate!

Just like the 90’s
Full-page refresh!!

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Fast Virtual DOM

Virtual DOM
Makes re-rendering on every change fast.

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Fast Virtual DOM

On every update…
• React builds a new virtual DOM subtree

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Fast Virtual DOM

On every update…
• React builds a new virtual DOM subtree
• …diffs it with the old one

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Fast Virtual DOM

On every update…
• React builds a new virtual DOM subtree
• …diffs it with the old one
• …computes the minimal set of DOM
mutations and puts them in a queue

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Fast Virtual DOM

On every update…
• React builds a new virtual DOM subtree
• …diffs it with the old one
• …computes the minimal set of DOM
mutations and puts them in a queue
• …and batch exexutes all updates
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Fast Virtual DOM

none to first
• Create Node:
<div
className="first"><span>A Span</span></div>

first to second

• Replace attribute:
className=“second"

className=“first" by

• Replace node:
Span</span> by <p>A Paragraph</p>

<span>A

second to none
• Remove Node:
<div
className="second"><p>A Paragraph</p></div>
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Fast Virtual DOM

Virtual DOM is simple and fast

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http://reactjs.org/
#reactjs on Freenode IRC
reactjs on Google Groups
Other helpful links:
• http://swannodette.github.io/2013/12/17/the-future-of-javascript-mvcs/
• https://news.ycombinator.com/item?id=6936975
• https://news.ycombinator.com/item?id=6937921
• http://calendar.perfplanet.com/2013/diff/
Thank You!!

React js

Editor's Notes

  • #2 No fb
  • #7 Or: mixing markup and display logic
  • #8 Or: mixing markup and display logic
  • #9 Or: mixing markup and display logic
  • #24 ----- Meeting Notes (9/9/13 12:00) ----- nowhere in this example is the dom node for count explicitly updated