Understanding Custom Directive in AngularJS
AngularJS allows you to create custom directives with which it becomes easier to encapsulate and simplify DOM manipulation in AngularJS. These directives extend the HTML functionality. Also, new directives can be created to manipulate the HTML behavior.
Following are the ways to implement custom directives in AngularJS :
1. Element directives
It is activated when finding a matching HTML element in the HTML template.
<my-directive></my-directive>
2. Attribute directives
It is activated when finding a matching HTML attribute in the template.
<div my-directive></div>
3. CSS Class directives
It is activated when finding a matching CSS Class.
<div class=”my-directive: expression;”></div>
4. Comment directives
It is enabled when finding a matching HTML comment.
<!-- Directive : my-directive expression; -->
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Commonly used properties
1. Restrict
It specify how a directive is implemented in angular app. There are 4 restrict options:
restrict : ‘A’ – attribute (default one) | <div my-directive></div>
restrict : ‘C’ – Class | <div class=”my-directive: expression;”></div>
restrict : ‘E’ – element | <my-directive></my-directive>
restrict : ‘M’ – Comment | <!– Directive : my-directive expression; –>
You can also specify multiple restrict like as follows:
restrict : ‘EC’
2. Scope
Scope accesses data or methods inside template and link function. By default the directives do not produce their own scope without explicitly set.
Different types of scopes are able to define which are as follows:
- scope : true – Get new scope
- scope : false – Use its parent scope
- scope : {} – Get new isolated scope that doesn’t inherit from parent and exists on its own
3. Template
It specify the HTML content that will be generated when directive is compiled.
4. TemplateUrl
It specify the path of template that should be used by directives.
details.directive('intellipaat', function () {
return {
restrict: 'E',
scope: false,
templateUrl: 'intellipaat'.tpl.html'
}
});
Example
<html>
<head>
<title>Angular JS Custom Directives</title>
</head>
<body>
<h1>AngularJS Custom Directives </h1>
<div ng-app = "detailsApp" ng-controller = "employeeController">
<employee name = "Mahesh"></employee><br/>
<employee name = "Piyush"></employee>
</div>
<script src = "http://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>
<script>
var detailsApp= angular.module("detailsApp", []);
detailsApp.directive('employee', function() {
var directive = {};
directive.restrict = 'E';
directive.template = "employee: <b>{{employee.name}}</b> , Id: <b>{{employee.id}}</b>";
directive.scope = {
employee: "=name"
}
directive.compile = function(element, attributes) {
element.css("border", "1px solid #cccccc");
var linkFunction = function($scope, element, attributes) {
element.html("Employee: <b>"+$scope.employee.name +"</b> , Id: <b>"+$scope.employee.id+"</b><br/>");
element.css("background-color", "#ffffff");
}
return linkFunction;
}
return directive;
});
detailsApp.controller('employeeController', function($scope) {
$scope.Mahesh = {};
$scope.Mahesh.name = "abc";
$scope.Mahesh.id = 1;
$scope.Piyush = {};
$scope.Piyush.name = "xyz";
$scope.Piyush.id = 2;
});
</script>
</body>
</html>
Output
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AngularJS Custom Directives
Employee: abc , Id: 1
Employee: xyz , Id: 2