Readme.md

Day 14 - Redux

Projects:

quiz-ngrx	Quiz app based on Redux

Working with immutable data

• How to define immutable entity?
  • We saw that we can create immutable entities by defining an interface where each property is readonly
• How to derive new object from existing one?
  • We saw that we can use several javscript tools to help us
  • Modifying object property using the spread operator (...) where we only specifiy the changed property

newObj = {...oldObj, prop1: newValue}

• Add item to array using the spread operator on arrays, so we create a new array which contains all the elements of the original array, with the new item.

newArray = [...oldArray, newValue];
newArray2 = [newValue, ...oldArray];

• Change item in array using either splice or map
• Remove item from array using either splice or filter
• We saw how to create helper functions to make our code more readable.

Redux and NgRx

• We learned about the core concepts of Redux
  • A State that holds the entire data in the application
  • A Store that stores the state and responsible to replace it with a new state after each action
  • An Action that the view dispatches in order to trigger a new state
  • A Reducer that calculates a new state from an existing one and an action, effectively turning out entire application into a state machine
  • A Selector that pulls a specific part of the state and serves it as an Observable
• We understood that redux belives in Uni-directional flow of data, where the store is the Single point of truth and data flows to it, and from it, through different routes
• We saw how to add @ngrx/store and @ngrx/store-devtools into our application
• We saw how to use the chrome extension for redux and how to configure the devtools to communicate with it
• We saw how to define the state
• We saw how to create a reducer from the initial state
• We saw how to define actions and how to group them under a namespace
• We saw how to define on parts in the reducer, that respond to specific actions and calculate the next state
• We saw how to dispatch actions from the components
• We saw how to define a hierarchy of selectors
  • We used createFeatureSelector to define the root selector
  • We used createSelector to create a selector from other more primitive selectors
• We saw how to use a selector to create observables which we can consume in the components