What the 

Flux is 

React

James Bjorkman




Facebook had a problem

Many People + Many Features + MVC
=
Really Bad Time

With each new feature

    • Predictability of codebase decreases.
    • Complexity of entire system grew more quickly.
    • Code was responsible for doing more things.
    • Data was used in more places.
    • Harder to bring new engineers up to speed.
    • System becomes harder to debug.
    • Harder to make changes confidently.
    • Harder to maintain and optimize.
    • Features take longer to build.
    • Code moves slower because it becomes more
    • and more fragile.


Hypothesis

By structuring code in a way 
that makes it more predictable
higher quality applications 
can be shipped in less time,
new engineers can be
brought up to speed quicker,
everyone can make 
changes more confidently.





Flux & React



Flux

Predictable Single Direction Data Flow

React

Declarative, Predictable, User Interfaces

Flux

Action -> Dispatcher -> Stores -> View

    1. User does Action
    2. Action builds payload & sends to Dispatcher
    3. Dispatcher gives payload to the registered Stores
    4. Store takes payload and deals with it.
    5. When a store changes, views rerender.




Whiteboard

// View (Trigger Action)
ItemActions.newItem('Bob');

// Action (Build Payload)
ItemActions = {
  newItem: function (title) {
    AppDispatcher.handleViewAction({
      actionType : ItemConstants.ITEM_CREATE,
      title      : title
    });
  }

};

// Store (Deal with payload)
AppDispatcher.register(function (payload) {
  var action = payload.action;
  switch (action.actionType) {
    case ItemConstants.ITEM_CREATE:
      createItem(action.title);   // Function handles ajax and all that
      break;
  }
  ItemStore.emitChange();         // Tell views to re-render
  return true;                    // Used for the Dispatcher Promises
});

REACT

    • Single Direction
    • Virtual Dom
    • Synthetic Events
    • Small Single Purpose Components
    • Easily Testable
    • Optimised Batch Updates of DOM
    • Push complexity of DOM mutations into framework
    • JSX
    • Virtual DOM representations can be rendered
      on the server and sent as the response.
    • Passed Properties From Above




WHITEBOARD

A SIMPLE Component

var React = require('react');

var HelloWorld = React.createClass({
  render: function () {
    return React.DOM.div({className: "HelloWorld"}, "Hello World");
  }
});

React.renderComponent(
  HelloWorld(),
  document.body
);

A Slightly More complex COMPONENT

var Counter = React.createClass({
  getInitialState: function () { return {count: 0} },
  render: function () {
    return React.DOM.div({className: "Coutner"}, [
      React.DOM.div({}, [
        this.state.count, 
        React.DOM.button( {onClick: this.inc}, '+1' )
      ])
    ]);
  },
  inc: function () {
    this.setState({count: this.state.count + 1}); 
  }
});

JSX

/** @jsx React.DOM */
var Counter = React.createClass({
  getInitialState: function () { return {count: 0} },
  render: function () {
    return (
      <div className="Counter">
        {this.state.count}
        <button onClick={ this.inc }>+1</button>
      </div>
    );
  },
  inc: function () {
    this.setState({count: this.state.count + 1}); 
  }
});

Components in Components

/** @jsx React.DOM */

var Counters = React.CreateClass({
  render: function () {
    return (
      <div>
        <h1>Counters</h1>
        <Counter />
        <Counter />
        <Counter />
        <Counter />
        <Counter />
      </div>
    );
  }
});

With Flux

var CounterStore   = require('./store/CounterStore');
var CounterActions = require('./actions/CounterActions');
function getState () { /* returns state from CounterStore */ }

var Counter = React.CreateClass({
  getInitialState: function () { return getState(); },
  componentWillMount: function () {
    CounterStore.on('CHANGE', this.updateState);
  },
  componentWillUnmount: function () {
    CounterStore.off('CHANGE', this.updateState);
  },
  updateState: function () { this.setState(getState()); },
  inc: function () { CounterActions.inc(this.state.id); },
  render: function () { /* Same as Before */ }
})




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