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About Yatin

Yatin Batra
The author is graduated in Electronics & Telecommunication. During his studies, he has been involved with a significant number of projects ranging from programming and software engineering to telecommunications analysis. He works as a technical lead in the information technology sector where he is primarily involved with projects based on Java/J2EE technologies platform and novel UI technologies.

JavaScript Array concat() Example

Greetings readers, in this tutorial, we will understand the array concat() method in the JavaScript language.

1. 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 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 JavaScript Array concat() Method

The array concat() method merges two or more arrays and returns a new array. This method does not replace anything in the original array but instead returns a shallow copy that contains copies of the elements combined from the original array. The method has the following syntax.

myArray.concat(array1, array2, .... , arrayN);

Where,

  • array1, array2, .... , arrayN represent the arrays to be combined

2. JavaScript Array concat() Example

Here is a systematic guide for implementing this tutorial using the JavaScript language.

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 Array concat() - Project Structure
Fig. 1: Application Project Structure

2.3 Project Creation

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

JavaScript Array concat() - Create a 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 Array concat() - Project Details
Fig. 3: Project Details

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

JavaScript Array concat() - Archetype Selection
Fig. 4: Archetype Selection

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 Array concat() - 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:

pom.xml

<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">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.javascript</groupId>
	<artifactId>JavascriptArrayconcat</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
</project>

3. Application Building

Let us create an application to understand the basic building blocks of this tutorial.

3.1 Define the HTML

Let us write a simple index page in the JavascriptArrayconcat/src/main/webapp/ folder. Add the following code to it:

index.jsp

<!-- JavaScript Array "concat()" example -->
<div id="title">
	<h4 class="text-info">What is a Array "concat()" method?</h4>
	<ul>
		<li>The javascript array <code>concat()</code> method combines two or more arrays and returns a new array.</li>
		<li>This method returns a <em>shallow copy</em> that contains copies of the same elements combines from the original arrays.</li>
		<li>Syntax: <pre>myArray.concat(array1, array2, ....., arrayN);</pre></li>
	</ul>
</div>
<div>  </div>

<p>Click the 'button' to join the arrays.</p>
<button id="btn_submit" type="button" class="btn btn-success" onclick="myfunction();">Click me</button>
<div>  </div>

3.2 Define the JavaScript function

Let us write a simple javascript function that will help developers understand the concat() method in the javascript language. Add the following code to it:

JavaScript function

// Javascript function to concat the two arrays.
function myfunction() {
	let realmadrid = ['Gareth Bale', 'Karim Benzema', 'Sergio Ramos'];
	let barcelona = ['Messi', 'Luis suarez	', 'Gerard Pique'];

	let players = realmadrid.concat(barcelona);
	document.getElementById("result").innerHTML = players;
}

3.3 First application

Complete the above steps and save the file. Let us see the sample code snippet.

index.jsp

<!DOCTYPE html>
<html lang="en">

<head>
    <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">
</head>

<body>
    <div class="container">
        <h2 align="center" class="text-danger">Array <code>concat()</code> method in JavaScript</h2>
        <hr />

        <!-- JavaScript Array "concat()" example -->
        <div id="title">
            <h4 class="text-info">What is a Array "concat()" method?</h4>
            <ul>
                <li>The javascript array <code>concat()</code> method combines two or more arrays and returns a new array.</li>
                <li>This method returns a <em>shallow copy</em> that contains copies of the same elements combines from the original arrays.</li>
                <li>Syntax: <pre>myArray.concat(array1, array2, ....., arrayN);</pre></li>
            </ul>
        </div>
        <div>  </div>

        <p>Click the 'button' to join the arrays.</p>
        <button id="btn_submit" type="button" class="btn btn-success" onclick="myfunction();">Click me</button>
        <div>  </div>

        <div id="result"></div>
    </div>
    <script>
    	// Javascript function to concat the two arrays.
        function myfunction() {
            let realmadrid = ['Gareth Bale', 'Karim Benzema', 'Sergio Ramos'];
            let barcelona = ['Messi', 'Luis suarez', 'Gerard Pique'];

            let players = realmadrid.concat(barcelona);
            document.getElementById("result").innerHTML = players;
        }
    </script>
</body>

</html>

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 Array concat() - 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 as shown in Fig. 7.

http://localhost:8082/JavascriptArrayconcat/

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

JavaScript Array concat() - Index page
Fig. 7: Index page

Users can click the button to display the result and can change the js function to debug the concat() method. That is all for this tutorial and I hope the article served you whatever you were looking for. Happy learning and do not forget to share.

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 understand the array concat() method in the javascript language.

Download
You can download the full source code of this example here: JavascriptArrayconcat
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