Some Notes on Redux from https://egghead.io/series/getting-started-with-redux

3 Main Principles

Single Immutable State Tree

All application state is contained in a single object tree which cannot be modified directly.

Actions

Actions are used to modify the app state tree. They're objects which describe changes. They only require a type key with other info to describe the change. Any data that will be represented by the app tree will get there via actions regardless of source (UX || Network).

{ type: "ADD_ITEM",
  index: 1,
  text: "hello world"
}

Reducer Functions

To describe state mutations, a single function must be written that takes the previous state of the app, the action being dispatched, and returns the next state of the app. This function has to be pure.

Accepts state and action where unknown actions should return the current state. If the state passed as undefined, the initial state should be returned.

Store

Combines these principles by holding onto the current application state object and allowing actions to be dispatched which will manage changes to the state. Can be initiated with createStore by specifying a reducer function.

Methods

getstate() returns the current state
dispatch({ type: 'SOME_ACTION' }) specify action objects to modify state
subscribe() registers a callback which is called when an action is dispatched