Saturday, 7 January 2017

AngularJS Directives

AngularJS Directives

AngularJS facilitates you to extend HTML with new attributes. These attributes are called directives.

There is a set of built-in directive in AngularJS which offers functionality to your applications. You can also define your own directives.

Directives are special attributes starting with ng- prefix. Following are the most common directives:

ng-app: This directive starts an AngularJS Application.
ng-init: This directive initializes application data.
ng-model: This directive defines the model that is variable to be used in AngularJS.
ng-repeat: This directive repeats html elements for each item in a collection.

ng-app directive

ng-app directive defines the root element. It starts an AngularJS Application and automatically initializes or bootstraps the application when web page containing AngularJS Application is loaded. It is also used to load various AngularJS modules in AngularJS Application.

See this example:

In following example, we've defined a default AngularJS application using ng-app attribute of a div element.

<div ng-app = "">  
   ...  
</div>  
  
   

ng-init directive

ng-init directive initializes an AngularJS Application data. It defines the initial values for an AngularJS application.

In following example, we'll initialize an array of countries. We're using JSON syntax to define array of countries.

<div ng-app = "" ng-init = "countries = [{locale:'en-IND',name:'India'}, {locale:'en-PAK',name:'Pakistan'}, {locale:'en-AUS',name:'Australia'}]">  
   ...  
</div>  

ng-model directive:

ng-model directive defines the model/variable to be used in AngularJS Application.

In following example, we've defined a model named "name".

<div ng-app = "">  
   ...  
   <p>Enter your Name: <input type = "text" ng-model = "name"></p>  
</div>  

ng-repeat directive

ng-repeat directive repeats html elements for each item in a collection. In following example, we've iterated over array of countries.

<div ng-app = "">  
   ...  
   <p>List of Countries with locale:</p>  
     
   <ol>  
      <li ng-repeat = "country in countries">  
         {{ 'Country: ' + country.name + ', Locale: ' + country.locale }}  
      </li>  
   </ol>  

AngularJS directives Example

Let's take an example to use all the above discussed directives:

<!DOCTYPE html>  
<html>  
<head>  
      <title>AngularJS Directives</title>  
</head>  
<body>  
      <h1>Sample Application</h1>  
        
      <div ng-app = "" ng-init = "countries = [{locale:'en-IND',name:'India'}, {locale:'en-PAK',name:'Pakistan'}, {locale:'en-AUS',name:'Australia'}]">   
         <p>Enter your Name: <input type = "text" ng-model = "name"></p>  
         <p>Hello <span ng-bind = "name"></span>!</p>  
         <p>List of Countries with locale:</p>  
        
         <ol>  
            <li ng-repeat = "country in countries">  
               {{ 'Country: ' + country.name + ', Locale: ' + country.locale }}  
            </li>  
         </ol>  
      </div>  
<script src = "http://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>  
</body>  
</html>  

AngularJS Directives List

AnglarJS directives are used to add functionality to your application. You can also add your own directives for your applications.

Following is a list of AngularJS directives:

Directive	Description
ng-app	It defines the root element of an application.
ng-bind	It binds the content of an html element to application data.
ng-bind-html	It binds the inner HTML of an HTML element to application data, and also removes dangerous code from the html string.
ng-bind-template	It specifies that the text content should be replaced with a template.
ng-blur	It specifies a behavior on blur events.
ng-change	It specifies an expression to evaluate when content is being changed by the user.
ng-checked	It specifies if an element is checked or not.
ng-class	It specifies css classes on html elements.
ng-class-even	It is same as ng-class, but will only take effect on even rows.
ng-class-odd	It is same as ng-class, but will only take effect on odd rows.
ng-click	It specifies an expression to evaluate when an element is being clicked.
ng-cloak	It prevents flickering when your application is being loaded.
ng-controller	It defines the controller object for an application.
ng-copy	It specifies a behavior on copy events.
ng-csp	It changes the content security policy.
ng-cut	It specifies a behavior on cut events.
ng-dblclick	It specifies a behavior on double-click events.
ng-focus	It specifies a behavior on focus events.
ng-hide	It hides or shows html elements.
ng-href	It specifies a URL for the <a> element.
ng-if	It removes the html element if a condition is false.
ng-include	It includes html in an application.
ng-init	It defines initial values for an application.
ng-jq	It specifies that the application must use a library, like jQuery.
ng-keydown	It specifies a behavior on keydown events.
ng-keypress	It specifies a behavior on keypress events.
ng-keyup	It specifies a behavior on keyup events.
ng-list	It converts text into a list (array).
ng-open	It specifies the open attribute of an element.
ng-options	It specifies <options> in a <select> list.
ng-paste	It specifies a behavior on paste events.
ng-pluralize	It specifies a message to display according to en-us localization rules.
ng-readonly	It specifies the readonly attribute of an element.
ng-required	It specifies the required attribute of an element.
ng-selected	It specifies the selected attribute of an element.
ng-show	It shows or hides html elements.
ng-src	It specifies the src attribute for the <img> element.
ng-srcset	It specifies the srcset attribute for the <img> element.
ng-style	It specifies the style attribute for an element.
ng-submit	It specifies expressions to run on onsubmit events.
ng-switch	It specifies a condition that will be used to show/hide child elements.
ng-transclude	It specifies a point to insert transcluded elements.
ng-value	It specifies the value of an input element.
ng-disabled	It specifies if an element is disabled or not.
ng-form	It specifies an html form to inherit controls from.
ng-model	It binds the value of html controls to application data.
ng-model-options	It specifies how updates in the model are done.
ng-mousedown	It specifies a behavior on mousedown events.
ng-mouseenter	It specifies a behavior on mouseenter events.
ng-mouseleave	It specifies a behavior on mouseleave events.
ng-mousemove	It specifies a behavior on mousemove events.
ng-mouseover	It specifies a behavior on mouseover events.
ng-mouseup	It specifies a behavior on mouseup events.
ng-non-bindable	It specifies that no data binding can happen in this element, or it's children.
ng-repeat	It defines a template for each data in a collection.

How to add directives

See this example:

<!DOCTYPE html>  
<html>  
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"></script>  
<body>  
  
<div ng-app="myApp" w3-test-directive></div>  
<script>  
var app = angular.module("myApp", []);  
app.directive("w3TestDirective", function() {  
    return {  
        template : "This is a directive constructor. "  
    };  
});  
</script>  
</body>  
</html>  

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