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About Yatin Batra

Yatin Batra
Yatin has graduated in Electronics & Telecommunication. During his studies, he has been involved with a large number of projects ranging from programming and software engineering to telecommunications analysis. He works as a software developer in the information technology sector where he is mainly involved with projects based on Java and J2EE technologies platform.

JavaScript Generators Example

Greetings readers! In this tutorial, we will explore the JavaScript Generators.

1. JavaScript Generators – Introduction

JavaScript is an object-oriented programming language that allows the client-side scripting to interact with a user and deliver the dynamic pages. Most web browsers including Google Chrome, Mozilla Firefox, Safari, Internet Explorer, Microsoft Edge, Opera, etc. support it. The JavaScript scripting language includes:

  • Declaring variables
  • Maintaining the retrieving values
  • Defining and invoking functions
  • Defining classes
  • Load and use external modules
  • Define event handlers
  • And much more ….

1.1 Advantages of JavaScript Language

The pros of using the JavaScript scripting language are:

  • JavaScript is easy to learn
  • It executes on the client’s browser, so eliminates the server-side processing and be executed on any OS
  • JavaScript can be used with any type of web page e.g. PHP, ASP.NET, Perl, etc
  • Web-page performance increases due to client-side execution
  • JavaScript code can be minified to decrease the loading time from the server
  • Many JavaScript-based application frameworks are available in the market to create Single page web applications e.g. AngularJS, ReactJS, etc

1.2 Disadvantages of JavaScript Language

The cons of using the JavaScript scripting language are:

  • Does not have any multi-threading or multi-processing capabilities
  • Does not allow the file reading and writing capabilities

1.3 Closures in JavaScript

Closures in javascript are the inner functions that give access to the outer function’s variables in addition to its own and global variables. In simple words, they are called inner functions. In this tutorial, we will create an anonymous function inside another anonymous function.

2. JavaScript Generators Example

Here is a systematic guide for implementing this tutorial.

2.1 Tools Used

We are using Eclipse Kepler SR2, JDK 8 and Maven. Having said that, we have tested the code against JDK 1.7, and it works well.

2.2 Project Structure

Firstly, let us review the final project structure if you are confused about where you should create the corresponding files or folder later!

JavaScript Generators - Project Structure
Fig. 1: Application Project Structure

2.3 Project Creation

This section will show how to create a Java-based Maven project with Eclipse. In Eclipse Ide, go to File -> New -> Maven Project.

JavaScript Generators - Maven Project
Fig. 2: Create a Maven Project

In the New Maven Project window, it will ask you to select the project location. By default, ‘Use default workspace location’ will be selected. Just click on the next button to proceed.

JavaScript Generators - Project Details
Fig. 3: Project Details

Select the ‘Maven Web App’ Archetype from the list of options and click next.

JavaScript Generators -  Archetype Parameters
Fig. 5: Archetype Parameters

It will ask you to ‘Enter the group and the artifact id for the project’. We will input the details as shown in the below image. The version number will be by default: 0.0.1-SNAPSHOT.

JavaScript Generators - Archetype Parameters
Fig. 5: Archetype Parameters

Click on Finish and the creation of a maven project is completed. If you see, it has downloaded the maven dependencies and a pom.xml file will be created. It will have the following code:


<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

3. Application Building

Let us see the sample code snippet to understand the closures in the javascript language.


<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

    <title>Index Page</title>
    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
    <script type="text/javascript">
    	// Javascript function.
        var incrementClickCount = (function() {
            var clickCount = 0;
            return function() {
                return ++clickCount;

    <div class="container">
        <h2 align="center" class="text-primary">JavaScript Closures Example</h2>
        <hr />
        <!------ JavaScript Closures Example ------>
        <div class="form-group">
            <!-- button. -->
            <button type="button" class="btn btn-primary" onclick="alert(incrementClickCount());">Click me</button>


4. Run the Application

As we are ready for all the changes, let us compile the project and deploy the application on the Tomcat7 server. To deploy the application on Tomat7, right-click on the project and navigate to Run as -> Run on Server.

JavaScript Generators - Deploy Application on Tomcat
Fig. 6: How to Deploy Application on Tomcat

Tomcat will deploy the application in its web-apps folder and shall start its execution to deploy the project so that we can go ahead and test it in the browser.

5. Project Demo

Open your favorite browser and hit the following URL to display the application’s index page and console output as shown in Fig. 7.


Server name (localhost) and port (8082) may vary as per your Tomcat configuration.

JavaScript Generators - Index page
Fig. 7: Index page

6. Conclusion

In this section, developers learned how to create a simple application with the JavaScript language. Developers can download the sample application as an Eclipse project in the Downloads section.

7. Download the Eclipse Project

This was a beginner’s tutorial to explore the JavaScript Generators.

You can download the full source code of this example here: JavaScript Generators Example
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1 year ago

Where is anything about Generators? This is crap!