Book Image

AngularJS Directives Cookbook

By : Fernando Monteiro, Jan Carlo Viray, Dror Elovits, Juri Strumpflohner, Gabriel Schenker
Book Image

AngularJS Directives Cookbook

By: Fernando Monteiro, Jan Carlo Viray, Dror Elovits, Juri Strumpflohner, Gabriel Schenker

Overview of this book

AngularJS directives are at the center of what makes it such an exciting – and important - web development framework. With directives, you can take greater control over HTML elements on your web pages – they ‘direct’ Angular’s HTML compiler to behave in the way you want it to. It makes building modern web applications a much more expressive experience, and allows you to focus more closely on improving the way that user interaction impacts the DOM and the way your app manages data. If you’re already using Angular, you probably recognize the power of directives to transform the way you understand and build your projects – but customizing and creating your own directives to harness AngularJS to its full potential can be more challenging. This cookbook shows you how to do just that – it’s a valuable resource that demonstrates how to use directives at every stage in the workflow. Packed with an extensive range of solutions and tips that AngularJS developers shouldn’t do without, you’ll find out how to make the most of directives. You’ll find recipes demonstrating how to build a number of different user interface components with directives, so you can take complete control over how users interact with your application. You’ll also learn how directives can simplify the way you work by creating reusable directives – by customizing them with Yeoman you can be confident that you’re application has the robust architecture that forms the bedrock of the best user experiences. You’ll also find recipes that will help you learn how to unit test directives, so you can be confident in the reliability and performance of your application. Whether you’re looking for guidance to dive deeper into AngularJS directives, or you want a reliable resource, relevant to today’s web development challenges, AngularJS Directives Cookbook delivers everything you need in an easily accessible way.
Table of Contents (16 chapters)
AngularJS Directives Cookbook
About the Author
About the Reviewers

Using the link function

Now let's take a look at the link function property inside the directive. The template generated by a directive is meaningless unless it is compiled with the appropriate scope. Thus, by default, a directive does not get a new child scope. Instead, it is related to the parent scope. This means that if the directive is present within a controller, then it will use this controller scope instead of creating a new one.

To use this scope, we need to use the link function. We achieve this by using the link property inside the directive definition. Let's use a basic example to understand this.

Getting ready

Let's place the following code inside a new blank HTML file:

<!DOCTYPE html>
<html ng-app="linkdirectives">

  <script src=""></script>
  <title>Link Function Directive</title>

  <body ng-controller="LinkCtrl">
    <input type="text" ng-model="colorName" placeholder="Insert a color name"/>


Now let's add the directive code.

How to do it…

Here's the directive code, using simple CSS manipulation:

    restrict: 'AE',
    replace: true,
    template: '<p style="background-color:{{colorName}}">Link Function Directive</p>',
    link: function(scope,element,attribute){

How it works…

The link function takes three arguments: scope, element, and attribute. For a better understanding, we use the entire name for the arguments, without any abbreviation. It is also very common to see elem for element and attrs for attribute.

The element argument is a short version from jQuery Lite that is already included in AngularJS to manipulate the DOM without the need to use the famous $() from jQuery.


AngularJS has a lightweight version of jQuery, called jQuery Lite.

The scope element is the same from the parent controller, and the link function is used for attaching event listeners to DOM elements. Always watch the model properties for changes, and update the DOM with the new information. In this case, we used the $apply() function to update the binding.

There's more…

The link function contains code used after the compilation process, such as some DOM manipulation or jQuery use. Also, the controller $scope and scope of the link function are almost the same thing.

When you use the scope element as the first parameter of the link function inside a directive, it has the same behavior of the $scope element from a controller. However, when you declare the scope: {} property with an empty object inside the directive, you create an isolate scope and both are different. We will see more about isolate scopes in the next chapter.

The controller $scope are parameters that are sent to the controller and they get there through Dependency Injection (DI). The scope of the link function are parameters sent to link and are standard order-based functions.

See also