AngularJS

AngularJS
AngularJS depends on the conviction that definitive programming should be used to make UIs and partner programming components,while fundamental composition PC projects is progressively able to describing an application business method of reasoning.The structure adjusts and stretches out conventional HTML to show dynamic substance through two-way information restricting that takes into account the programmed syncronization of models and perspectives. As a result,AngularJS de-stresses unequivocal Document Item Model (DOM) control with the objective of improving testability and execution.
AngularJS's design goals include :
*To decouple DOM manipulation from application logic.The difficulty of this is dramatically affected by the code is structured.
* To decouple the customer side of an application from the server side.This permits advancement work to advance in parallel, and takes into consideration reuse of the two sides.
*To provide structure for the journey of building an application from designing the UI,through writing the business logic,to testing.
AngularJS comprehends the MVC manual for discrete presentation, data and reason portions.Using dependence injection,Angular brings generally server-side services,such as view-subordinate controllers,to client side web applications.Consequently,much of the weight on the server can be diminished.
Scope
AngularJS utilizes the expression "scope" in a way much the same as the basics of software engineering.
Scope in computer science describes when in the program a particular binding is valid.The ECMA-262 specification defines scope as: a lexical environment in which a Function object is executed in client-side web scripts;akin to how scope is defined in lamda calculus.
As a piece of the "MVC" engineering, the extension frames the "Model", and all factors characterized in the degree can be gotten to by the "View" just as the Controller". The extension carries on as a paste and ties the "View" and the "Controller".
In AngularJS, "scope" is a certain kind of object that itself can be in scope or out of scope in any given part of the program,following the variable scope in JavaScript like any other object. At the point when the expression "scope" is utilized below,it alludes to the Angular degree object and not the extent of a name official.
Bootstrap
The task performed by the AngularJS bootstrapper occur in three phrases after the DOM has been loaded :

*Creation of a new Injector
*Compilation of the directives that decorate the DOM
*Linking of all directives to scope.
AngularJS orders enable the engineer to indicate custom and reusable HTML-like components and properties that characterize information authoritative and the conduct of introduction parts.Some of the most commonly used directives are :
ng-animate
A module offers help for Javascript,CSS3 progress and CSS3 keyframe activity snares inside existing center and custom mandates.
Since ng-* attributes are not valid in HTML specifications, data-ng-* can also be used as a prefix.For example, both ng-app and data-ng-app are valid in AngularJS.
ng-app
Declares the root element of an AngularJS application,under which directives can be used to declare bindings and define behaviour.
ng-aria
A module for accessibility support for common ARIA attributes.
ng-bind
Sets the content of a DOM component to the estimation of an articulation.For example, displays the value of 'name' inside the span element.Any change to the variable 'name' in the application's scope reflect instantly in the DOM.
ng-class
Conditionally apply a class,depending on the value of a boolean expression.
ng-controller
Specifies a Javascript controller class that evaluates HTML expressions.
ng-if
Basic if statement directive that instantiates the following element if the condition are true.When the condition is false,the element is removed from the DOM.When true,a clone of the compiled element is re-inserted.
ng-init
Called once when the element is initialized.
ng-model
Similar to ng-bind,but establishes two-way data binding between the view and the scope.

ng-model-options
Provides turning for how model updates are done.
ng-repeat
Instantiate an element once per item from a collection.
ng-show and ng-hide
Conditionally show or hide an element,depending on the value of a boolean expression.Show and hide is achieved by setting the CSS dispaly style.
ng-switch
Conditionally instatiate one template from a set of choices,depending on the value of a selection expression.
ng-view
The base directive responsible for handling routes that resolve JSON before rendering templates driven by specified controllers.
Two-way data binding
AngularJS two-way data binding is its most notable feature,largely relieving the server backend of templating responsibilities,Instead,templates are rendered in plain HTML according to data contained in a scope defined in the model.The $scope service in Angular detects changes to the model section and modifiers HTML expressions in the view via a controller.Likewise,any alterations to the view are reflcted in the model.This circumvents the need to actively manipulate the DOM and encourages bootstrapping and rapid prototyping of web applications.AngularJS detects changes in models by comparing the current values stored earlier in a process of dirty-checking,unlike Ember.js and Backbone.js that trigger listeners when the model values are changes.
Performance
AngularJS set a out the paradigm of a digest cycle.This cycle can be considered a loop,during which AngularJS checks if there is any change to all the variables watched by all the $scopes.If $scope.myVar is defined in a controller and this variable was marked for watching,Angular will monitor the changes on myVar in each loop interaction..