Cortex is a Javascript library for centrally managing data with React.

Key features:

• supports deeply nested data with a simple API
• performs old and new data comparison out of the box so you don't have to implement shouldComponentUpdate
• performs batch updates and efficiently rewraps only the affected subtree.
• has built-in methods for working with arrays and hashes

Demos

skyline (4-level nested components)

file system (arbitrarily deep structure of a single component type)

Initialize a cortex object

var data = {a: 100, b: [1, 2, 3]};

var cortex = new Cortex(data, function() {
  //trigger your React component to update props
});

Get a nested cortex object

cortex.a

//Also works
cortex['a']

Get a nested cortex element in an array

cortex.b[0]

Get the actual value

cortex.a.getValue()
// ==> 100

Change data

cortex.a.set(200);
cortex.a.getValue();
// ==> 200

Add callbacks

cortex.on("update", myCallback);

Remove callback

cortex.off("update", myCallback);

Remove all callbacks

cortex.off("update");

In React's world data flows in one direction from the top down. That means if you want to make a change, change it at the source and let it propagate down the chain. But what happen when a child component needs to update the data? React's official guideline is to use callback for communication between parent and child components.

However, this simply isn't sustainable even for trivially nested data. Imagine a Restaurant app in which the Restaurant has many Orders, each has many Items, each of which has many Modifiers. If you want to update a Modifier from 'medium rare' to 'well-done' you'd have to pass the data changes several levels up. This is not only awkward but also creates unnecessary extra code in each component in the chain only for the purpose of passing data upstream.

Cortex's goal is to support arbitrarily deep data structure without requiring you to pass callbacks down the chain. Cortex achieves this by thinly wrap your data in an object that contains the key for locating each nested piece of data as accessed from the top level. When you change the data, internally Cortex passes the new value along with its location key to update the data at the source.

The following example has two components Order and Item components. An Order contains an array of Items, and each Item can increase its own quantity attribute.

var Item = React.createClass({
  increase: function() {
    var quantity = this.props.item.quantity.getValue();
    this.props.item.quantity.set(quantity + 1);
  },
  subTotal: function() {
    return this.props.item.quantity.getValue() * this.props.item.price.getValue();
  },
  render: function() {
    return(
      <div className="item">
        <a href="#" onClick={this.increase}>+</a>
        <span>{this.props.item.quantity.getValue()}</span>
        <span>{this.props.item.name.getValue()}</span>
        <span>${this.subTotal()}</span>
      </div>
    );
  }
});

var Order = React.createClass({
  render: function() {
    var items = this.props.order.map(function(item){
      return <Item item={item} />;
    });
    return(
      <div>{items}</div>
    );
  }
});

var orderData = [
      {name: "Burger", quantity: 2, price: 5.0},
      {name: "Salad", quantity: 1, price: 4.50},
      {name: "Coke", quantity: 3, price: 1.50}
    ];

//Initialize cortex with data and pass in a callback to run when data is updated.
var orderCortex = new Cortex(orderData);

var orderComponent = React.renderComponent(
  <Order order={orderCortex} />, document.getElementById("order")
);

orderCortex.on("update", function(updatedOrder) {
  orderComponent.setProps({order: updatedOrder});
});

First we initialize cortex with:

var orderCortex = new Cortex(orderData);

Then it's passed into the Order component to render the Item components.

We set a callback to run on update event using

orderCortex.on("update", function(updatedOrder) {
  orderComponent.setProps({order: orderCortex});
});

In Item component, note that we display the quantity value with this.props.item.quantity.getValue(). This is because this.props.item.quantity only gives us the wrapper of the quantity attribute, we need to call getValue() to get the actual value.

In increase method, we use this.props.item.quantity.set(quantity + 1) to add 1 to the current quantity value.

new Cortex(data, function() {
  //trigger your React component to update
});

Method                    | Description
--------------------------|:-------------------
`getValue()`              | Returns the actual value
`val()`                   | Alias for `getValue`
`set(value)`              | Changes the value and rewrap the subtree.
`remove()`                | Self destruct method: remove self from parent if nested, set value to undefined if root level.
`.on("update", callback)` | Add a callback to run on update event.
`.off("update", callback)`| Remove a callback. If no callback is specified, all existing callbacks will be removed.

Method                         | Description
-------------------------------|:----------------------
`count()`                      | Returns length of nested wrappers
`forEach(callback)`            | Iterates over all elements. The callback accepts the following input `(wrapperElement, index, wrapperArray)`
`map(callback)`                | Returns a new array as returned by the callback. Callback accepts same input as forEach callback
`find(callback)`               | Returns the first wrapper element that meets the condition returned by callback. Callback accepts same input as forEach callback.
`findIndex(callback)`          | Returns index of first wrapper element that meets condition returned callback. Callback accepts same input as forEach callback.
`push(value)`                  | Inserts and rewrap the value at the end of the array.
`pop()`                        | Removes the last element in the array
`unshift(value)`               | Inserts and rewrap the value at the front of the array.
`shift()`                      | Removes the first element in the array
`insertAt(index, [value])`     | Inserts a value or an array of values starting at specified index.
`removeAt(index, howMany = 1)` | Removes specified number of elements starting at index location. By default it removes 1 element if number of elements to be removed isn't specified.

Methods                        | Description
-------------------------------|:------------------------
`keys()`                       | Returns the array of keys
`values()`                     | Returns the array of values
`hasKey(key)`                  | Returns boolean value whether the key exists
`forEach(callback)`            | Iterates over every key and value pair. The callback accepts the following inputs `(key, wrapperElement)`
`destroy(key)`                 | Removes the specified key and value pair
`add(key, value)`              | Adds the specified key and value pair

bower install cortexjs

Reference the js file

<script src="/bower_components/cortexjs/build/cortex.js"></script>

Install via npm

npm install cortexjs

Use it:

Cortex = require("cortexjs");

wrappedData = new Cortex({mydata: 1});
console.log(wrappedData.mydata.getValue()); //1

wrappedData.mydata.set(100);
console.log(wrappedData.mydata.getValue()); //100

To build Cortex:

gulp

To run test:

gulp test

To compile jsx files in examples into js files:

gulp react

Besides providing the convenience of allowing you to update data from any level Cortex also has several optimizations that help boost performance.

When you issue a set(newValue) call, no data actually change at that point. What happens internally is the wrapper being called publishes a notification to the master cortex wrapper passing along a payload consisting of the path for locating the data and the new value (Yes, there is a pub/sub system within Cortex.) The master wrapper then performs a deep comparison between the old and new data to determine whether it should trigger the update action. If no change was made, the process just exits without touching the data nor invoking the callbacks.

Deep comparison may sound costly but in practice when you call set(newValue) the newValue usually isn't deeply nested (if it is and the actual change is many layers deep then you should consider calling set(newValue) on the wrapper at the level that the change actually occurs.) In some situations where you have to pass in arbirarily deeply nested value the comparison work is still worth it because it can potentially save you from unnecessarily rewrapping and triggering React to update.

After the newValue is determined to be different, besides updating the raw data Cortex will need to rebuild the nested wrapper objects. This process is called rewrapping. Since rewrapping the entire data tree is inefficient and unnecessary, and since cortex already has the path to locate the affected piece of data it simply rewraps the affected subtree.

When multiple updates occur at the same time, it will result in the same number of callback invocations, which usually involve triggering React to update that same number of times. While React has good diffing algorithm for efficiently redrawing the DOM it would be even more efficient if React doesn't have to perform DOM comparison mutliple times. Cortex avoid triggering React by running callback only once for updates happening at the same time.

If multiple updates happen in the same subtree, then it's possible to deduce the least deep node (the node closest to the root) that contains all the changes and rewrap at that node's subtree. This is especially useful when an array is being updated one element at a time or a deeply nested piece of data change at multiple levels. Under this scheme, we only have to rewrap once at the top node instead individually rewrapping every updated element subtrees.