{"id":72347,"date":"2020-01-13T17:47:43","date_gmt":"2020-01-13T12:17:43","guid":{"rendered":"https:\/\/www.vskills.in\/certification\/tutorial\/?p=72347"},"modified":"2024-04-12T14:22:53","modified_gmt":"2024-04-12T08:52:53","slug":"basic-angularjs-directives","status":"publish","type":"page","link":"https:\/\/www.vskills.in\/certification\/tutorial\/basic-angularjs-directives\/","title":{"rendered":"Basic AngularJS Directives"},"content":{"rendered":"

AngularJS directives are extended HTML attributes with the prefix ng-. The ng-app directive initializes an AngularJS application. The ng-init directive initializes application data.<\/p>\n

The ng-model directive binds the value of HTML controls (input, select, textarea) to application data.<\/p>\n

Example<\/strong><\/p>\n

<div ng-app=”” ng-init=”firstName=’Demo'”><\/p>\n

<p>Name: <input type=”text” ng-model=”firstName”><\/p><\/p>\n

<p>You wrote: {{ firstName }}<\/p><\/p>\n

<\/div><\/p>\n

The ng-app directive also tells AngularJS that the <div> element is the “owner” of the AngularJS application.<\/p>\n

Data Binding<\/h4>\n

The {{ firstName }} expression, in the example above, is an AngularJS data binding expression. Data binding in AngularJS binds AngularJS expressions with AngularJS data. {{ firstName }} is bound with ng-model=”firstName”.<\/p>\n

In the next example two text fields are bound together with two ng-model directives:<\/p>\n

Example<\/strong><\/p>\n

<div ng-app=”” ng-init=”quantity=1;price=5″><\/p>\n

Quantity: <input type=”number” ng-model=”quantity”><\/p>\n

Costs:\u00a0\u00a0\u00a0 <input type=”number” ng-model=”price”><\/p>\n

Total in dollar: {{ quantity * price }}<\/p>\n

<\/div><\/p>\n

Using ng-init is not very common.<\/p>\n

Repeating HTML Elements<\/h4>\n

The ng-repeat directive repeats an HTML element:<\/p>\n

Example<\/strong><\/p>\n

<div ng-app=”” ng-init=”names=[‘Jani’,’Hege’,’Kai’]”><\/p>\n

<ul><\/p>\n

<li ng-repeat=”x in names”><\/p>\n

{{ x }}<\/p>\n

<\/li><\/p>\n

<\/ul><\/p>\n

<\/div><\/p>\n

The ng-repeat directive actually clones HTML elements once for each item in a collection. The ng-repeat directive used on an array of objects:<\/p>\n

Example<\/strong><\/p>\n

<div ng-app=”” ng-init=”names=[<\/p>\n

{name:’Jani’,country:’Norway’},<\/p>\n

{name:’Hege’,country:’Sweden’},<\/p>\n

{name:’Kai’,country:’Denmark’}]”><\/p>\n

<ul><\/p>\n

<li ng-repeat=”x in names”><\/p>\n

{{ x.name + ‘, ‘ + x.country }}<\/p>\n

<\/li><\/p>\n

<\/ul><\/p>\n

<\/div><\/p>\n

AngularJS is perfect for database CRUD (Create Read Update Delete) applications. Just imagine if these objects were records from a database.<\/p>\n

The ng-app Directive<\/h4>\n

The ng-app directive defines the root element of an AngularJS application. The ng-app directive will auto-bootstrap (automatically initialize) the application when a web page is loaded.<\/p>\n

The ng-init Directive<\/h4>\n

The ng-init directive defines initial values for an AngularJS application. Normally, you will not use ng-init. You will use a controller or module instead.<\/p>\n

The ng-model Directive<\/h4>\n

The ng-model directive binds the value of HTML controls (input, select, textarea) to application data. The ng-model directive can also:<\/p>\n

    \n
  • Provide type validation for application data (number, email, required).<\/li>\n
  • Provide status for application data (invalid, dirty, touched, error).<\/li>\n
  • Provide CSS classes for HTML elements.<\/li>\n
  • Bind HTML elements to HTML forms.<\/li>\n<\/ul>\n

    With the ng-model directive you can bind the value of an input field to a variable created in AngularJS.<\/p>\n

    Example<\/strong><\/p>\n

    <div ng-app=”myApp” ng-controller=”myCtrl”><\/p>\n

    Name: <input ng-model=”name”><\/p>\n

    <\/div><\/p>\n

    <script><\/p>\n

    var app = angular.module(‘myApp’, []);<\/p>\n

    app.controller(‘myCtrl’, function($scope) {<\/p>\n

    $scope.name = “Demo User”;<\/p>\n

    });<\/p>\n

    <\/script><\/p>\n

    Two-Way Binding<\/u> – The binding goes both ways. If the user changes the value inside the input field, the AngularJS property will also change its value:<\/p>\n

    Example<\/strong><\/p>\n

    <div ng-app=”myApp” ng-controller=”myCtrl”><\/p>\n

    Name: <input ng-model=”name”><\/p>\n

    <h1>You entered: {{name}}<\/h1><\/p>\n

    <\/div><\/p>\n

    Validate User Input<\/u> – The ng-model directive can provide type validation for application data (number, e-mail, required):<\/p>\n

    Example<\/strong><\/p>\n

    <form ng-app=”” name=”myForm”><\/p>\n

    Email:<\/p>\n

    <input type=”email” name=”myAddress” ng-model=”text”><\/p>\n

    <span ng-show=”myForm.myAddress.$error.email”>Not a valid e-mail address<\/span><\/p>\n

    <\/form><\/p>\n

    In the example above, the span will be displayed only if the expression in the ng-show attribute returns true.<\/p>\n

    If the property in the ng-model attribute does not exist, AngularJS will create one for you.<\/p>\n

    Application Status<\/u> – The ng-model directive can provide status for application data (invalid, dirty, touched, error):<\/p>\n

    Example<\/strong><\/p>\n

    <form ng-app=”” name=”myForm” ng-init=”myText = ‘post@myweb.com'”><\/p>\n

    Email:<\/p>\n

    <input type=”email” name=”myAddress” ng-model=”myText” required><\/p>\n

    <h1>Status<\/h1><\/p>\n

    {{myForm.myAddress.$valid}}<\/p>\n

    {{myForm.myAddress.$dirty}}<\/p>\n

    {{myForm.myAddress.$touched}}<\/p>\n

    <\/form><\/p>\n

    CSS Classes<\/u> – The ng-model directive provides CSS classes for HTML elements, depending on their status:<\/p>\n

    Example<\/strong><\/p>\n

    <style><\/p>\n

    input.ng-invalid {<\/p>\n

    background-color: lightblue;<\/p>\n

    }<\/p>\n

    <\/style><\/p>\n

    <body><\/p>\n

    <form ng-app=”” name=”myForm”><\/p>\n

    Enter your name:<\/p>\n

    <input name=”myName” ng-model=”myText” required><\/p>\n

    <\/form><\/p>\n

    The ng-model directive adds\/removes the following classes, according to the status of the form field:<\/p>\n

    ng-empty<\/p>\n

    ng-not-empty<\/p>\n

    ng-touched<\/p>\n

    ng-untouched<\/p>\n

    ng-valid<\/p>\n

    ng-invalid<\/p>\n

    ng-dirty<\/p>\n

    ng-pending<\/p>\n

    ng-pristine<\/p>\n

    Create New Directives<\/h4>\n

    In addition to all the built-in AngularJS directives, you can create your own directives. New directives are created by using the .directive function.<\/p>\n

    To invoke the new directive, make an HTML element with the same tag name as the new directive.<\/p>\n

    When naming a directive, you must use a camel case name, w3TestDirective, but when invoking it, you must use – separated name, w3-test-directive:<\/p>\n

    Example<\/strong><\/p>\n

    <body ng-app=”myApp”><\/p>\n

    <w3-test-directive><\/w3-test-directive><\/p>\n

    <script><\/p>\n

    var app = angular.module(“myApp”, []);<\/p>\n

    app.directive(“w3TestDirective”, function() {<\/p>\n

    return {<\/p>\n

    template : “<h1>Made by a directive!<\/h1>”<\/p>\n

    };<\/p>\n

    });<\/p>\n

    <\/script><\/p>\n

    <\/body><\/p>\n

    You can invoke a directive by using:<\/p>\n

      \n
    • Element name<\/li>\n
    • Attribute<\/li>\n
    • Class<\/li>\n
    • Comment<\/li>\n<\/ul>\n

      The examples below will all produce the same result:<\/p>\n

      Element name<\/u><\/p>\n

      <w3-test-directive><\/w3-test-directive><\/p>\n

      Attribute<\/u><\/p>\n

      <div w3-test-directive><\/div><\/p>\n

      Class<\/u><\/p>\n

      <div class=”w3-test-directive”><\/div><\/p>\n

      Comment<\/u><\/p>\n

      <!– directive: w3-test-directive –><\/p>\n

      Restrictions<\/h4>\n

      You can restrict your directives to only be invoked by some of the methods.<\/p>\n

      Example<\/strong><\/p>\n

      By adding a restrict property with the value “A”, the directive can only be invoked by attributes:<\/p>\n

      var app = angular.module(“myApp”, []);<\/p>\n

      app.directive(“w3TestDirective”, function() {<\/p>\n

      return {<\/p>\n

      restrict : “A”,<\/p>\n

      template : “<h1>Made by a directive!<\/h1>”<\/p>\n

      };<\/p>\n

      });<\/p>\n

      The legal restrict values are:<\/p>\n

        \n
      • E for Element name<\/li>\n
      • A for Attribute<\/li>\n
      • C for Class<\/li>\n
      • M for Comment<\/li>\n<\/ul>\n

        By default the value is EA, meaning that both Element names and attribute names can invoke the directive.<\/p>\n","protected":false},"excerpt":{"rendered":"

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Example <div ng-app=”” ng-init=”firstName=’Demo’”> <p>Name: <input type=”text” ng-model=”firstName”><\/p> <p>You wrote: {{ firstName }}<\/p> <\/div> The ng-app directive…<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"categories":[8417],"tags":[8431],"class_list":["post-72347","page","type-page","status-publish","hentry","category-angular-js-web-development","tag-basic-angularjs-directives"],"acf":[],"yoast_head":"\nBasic AngularJS Directives - Tutorial<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.vskills.in\/certification\/tutorial\/basic-angularjs-directives\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Basic AngularJS Directives - Tutorial\" \/>\n<meta property=\"og:description\" content=\"AngularJS directives are extended HTML attributes with the prefix ng-. 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