AngularJS Note Series (iv) Controllers and expressions

Controller: In Angular the controller is a function used to add additional functionality to the scope. We use it to set the initial state of the scope object and add custom behavior.

How to use: var app = Angualr.module (' app ', []);

App.controller (' TestController ', function ($scope) {

Do sth here
})

Controller nesting: A parent scope exists throughout the application, and all scopes inherit from the prototype, except for the orphaned scope. They all have access to the parent scope.

By default, when AngularJS cannot find a property in the current scope, it looks up and goes back to $rootscope, and if it is not found, the program continues to run, but the view cannot be updated.

Best practice: Dapper, you should not manipulate DOM and data too much in the controller. Complex business logic should be put into services and views.

Expression: In Angular, the way we bind variables to $scope through {{}} is essentially an expression. When listening with $watch, Angular will perform operations on functions or expressions.

Parse expression: Angular parses an expression by $parse the internal service, $interpolate the service returns a function that is used to operate the expression in a particular context.

<DivNg-controller= "Mycontroller">       <inputNg-model= "to"type= "Email"placeholder= "Recipient" />       <textareaNg-model= "Emailbody"></textarea>       <Pre>{{Previewtext}}</Pre></Div>

Angular.module (' myApp ', [])       . Controller (function($scope, $interpolate) {//  function(body) {           if  (body) {             var template = $ Interpolate (body);              =               Template ({to: $scope. to});           

AngularJS Note Series (iv) Controllers and expressions