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• Expressions

  • Expressions are similar to like the result of an eval(javascript) (roughly). They are processed by Angular and, therefore, have these important, distinct properties:
    • All expressions are executed in the context of the scope and have access to local $scope variables.
    • They do not throw errors if an expression results in a TypeError or a ReferenceError.
    • They do not allow for any control flow functions (conditionals; e.g., if/else).
    • They can accept a filter and/or filter chains

• Controllers

  • The controller in AngularJS is a function that adds additional functionality to the scope of the view. They are used to set up an initial state and to add custom behavior to the scope object.
  • To create custom actions we can call in our views, we can just create functions on the scope of the controller.

Services

• Services provide a method for us to keep data around for the lifetime of the app and communicate across controllers in a consistent manner.
• Services are singletons objects that are instantiated only once per app (by the $injector) and lazy-loaded (only created when necessary). They provide an interface to keep together methods that relate to a specific function.

The most common and flexible way to create a service uses the angular.module API factory:

// Example service that holds on to the current_user for the lifetime of the app
angular.module('myApp.services', [])
  .factory('UserService', ['$http', function($http) {

    var current_user;

    return {
      getCurrentUser: function() {
        return current_user;
      },
      setUsername: function(user) {
        current_user; = user;
      }
    }

  }]);

Building

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• Data Binding

  • Due to the nature of javascript itself and how it passes by value vs. reference, it's considered a best- practice in Angular to bind references in the views by an attribute on an object, rather than the raw object itself.

• Services

  • If you want your function to be called like a normal function, use factory. If you want your function to be instantiated with the new operator, use service. If you don't know the difference, use factory. Service or Factory?

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