jQuery

jQuery Traversing Example

Greetings readers, in this tutorial, we will show how to use the jQuery library and the different traversing methods to traverse through the HTML DOM using jQuery.

1. Introduction

jQuery is nothing but a JavaScript library that comes with rich functionalities. It is small and faster than many JavaScript code written by an average web developer. By using jQuery developers can write less code and do more things, making web developer’s tasks very easy. In simple word, jQuery is a collection of several useful methods, which can be used to carry out many common tasks in JavaScript. A couple of lines of jQuery code can do things which need too many JavaScript lines to do. The true power of jQuery comes from its CSS-like selector, which allows it to select any element from DOM and change, update or manipulate it. Developers can use jQuery to do cool animations like fade in or fade out. They can also change the CSS class of a component dynamically e.g. making a component active or inactive. I have used this technique to make tabbed UI in HTML. I can vouch for jQuery that once developers start using it, they will never go back to plain old JavaScript as jQuery is clear, concise, and powerful.

1.1 Why jQuery?

  • It helps in improving the application performance and increasing the developer’s productivity
  • It helps in developing the browser compatible web-page
  • It helps in implementing the UI related critical functionality without writing the several lines of codes
  • It is fast and extensible i.e. developers can use the jQuery library to implement the customized behavior
  • It is simpler and easy to learn

1.2 jQuery Traversing Methods

The jQuery library provides several traversing methods to traverse the HTML DOM elements in a DOM hierarchy. The following table lists the jQuery methods for traversing the DOM elements.

jQuery MethodsDescription
children()Get all the child elements of the specified element(s)
each()Iterate over specified elements and execute the specified call back function for each element
find()Get all the specified child elements of each specified element(s)
first()Get the first occurrence of the specified element
next()Get the immediately following sibling of the specified element
parent()Get the parent of the specified element(s)
prev()Get the immediately preceding sibling of the specified element
siblings()Get the siblings of each specified element(s)

 
The following figure shows how the jQuery traversing methods get the DOM elements.

jQuery Traversing - Traversing the DOM elements
Fig. 1: Traversing the DOM elements

These new APIs make a developer life easier, really! But it would be difficult for a beginner to understand this without an example. Therefore, let us create a simple application using the jQuery library.

2. jQuery Traversing Example

Here is a systematic guide for implementing this tutorial using the jQuery library.

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!

jQuery Traversing - Application Project Structure
Fig. 2: 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.

jQuery Traversing - Create a Maven Project
Fig. 3: Create a Maven Project

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

jQuery Traversing - Project Details
Fig. 4: Project Details

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

jQuery Traversing - Archetype Selection
Fig. 5: 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.

jQuery Traversing - Archetype Parameters
Fig. 6: 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.jquery</groupId>
	<artifactId>jQueryTraversing</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 Load the jQuery Library

Since it is a pure JavaScript framework, so developers should add its reference using the <script> tag.

<script type="text/javascript" src="resource/js/jquery-3.3.1.min.js"></script>

Developers can either download the jQuery from the official website and the application will then directly load the jQuery library from the local drive or they can also include the direct CDN link under the script tag.

3.2 Define the Application

Next, we will define the sample application using the HTML tags.

<div id="start_message">
	<h4 class="text-primary text-align">This demo is for the different traversing methods in jQuery</h4>
</div>
<div> </div>

<div id="technoStackList">
	<p><strong>The Web-Development Technological stack list</strong></p>		    
	<ul id="technoStack" class="list-group list-group-flush">	            
		<li id="tech1" class="list-group-item">jQuery</li>
		<li id="tech2" class="list-group-item">AngularJs</li>
		<li id="tech3" class="list-group-item">HTML/CSS</li>
		<li id="tech4" class="list-group-item">JavaScript</li>
		<li id="tech5" class="list-group-item">NodeJs</li>
	</ul>
</div>			

<div id="end_message">
	<h4 class="text-primary text-align">Thank you for your visit. Have a great day! ☺</h4>
</div>

3.3 Define a jQuery Function

In this step, we’ll demonstrate the jQuery traversing methods that will display the results in an alert message box. Add the following code to the jQuery function.

$(document).ready(function() {

	// each() function
	$("#each").click(function() {
		$("li").each(function(index) {
			alert('Index= ' + index + ', Text= ' + $(this).text());
		});
	});

	// children() function
	$("#children").click(function() {
		$("#technoStackList").children().each(function (index) {
			alert('Index= ' + index + ', Text= ' + $(this).text());
		});
	});

	// find() function
	$("#find").click(function() {
		$("#technoStackList").find("li").each(function(index){
			alert('Index= ' + index + ', Text= ' + $(this).text());
		});
	});

	// next() function
	$("#next").click(function() {
		alert('Next element to "technoStackList" id is= ' + $("#technoStackList").next().text());
	});

	// parent() function
	$("#parent").click(function() {
		alert('Parent element of "technoStack" id is= ' + $("#technoStack").parent().html());
	});

	// siblings() function
	$("#siblings").click(function() {
		$("#technoStackList").siblings().css({"font-size": "35px", "font-style": "italic"});
	});

});

3.4 First jQuery Application

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

index.jsp

<!DOCTYPE html>
<html lang="en">
	<head>
	    <title>IndexPage</title>
	    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
	
	    <!-- ==== Css files ==== -->
	    <link rel="stylesheet" type="text/css" href="https://www.webcodegeeks.com/wp-content/litespeed/localres/aHR0cHM6Ly9tYXhjZG4uYm9vdHN0cmFwY2RuLmNvbS8=bootstrap/4.1.3/css/bootstrap.min.css">
	    <link rel="stylesheet" type="text/css" href="resource/css/mystyle.css">
	
	    <!-- ==== JavaScript files ==== -->
	    <script src="resource/js/jquery-3.3.1.min.js"></script>
	    <script src="resource/js/mystyle.js"></script>
	</head>
	<body>
	    <div class="container">
	        <h2 class="text-primary text-align">jQuery Traversing Methods</h2><hr />
	        
	        <!-- ==== jQuery Traversing Methods Example ====  -->
	        <div class="three-inline-btns">
	            <div class="inner">
	                <button id="each" type="submit" class="btn btn-default">each()</button>
	            </div>
	            <div class="inner">
	                <button id="children" type="submit" class="btn btn-default">children()</button>
	            </div>
	            <div class="inner">
	                <button id="find" type="submit" class="btn btn-default">find()</button>
	            </div>
	            <div class="inner">
	                <button id="next" type="submit" class="btn btn-default">next()</button>
	            </div>
	            <div class="inner">
	                <button id="parent" type="submit" class="btn btn-default">parent()</button>
	            </div>
	            <div class="inner">
	                <button id="siblings" type="submit" class="btn btn-default">siblings()</button>
	            </div>
	        </div>
	        <div> </div>
	        
	        <div id="start_message">
			    <h4 class="text-primary text-align">This demo is for the different traversing methods in jQuery</h4>
			</div>
			<div> </div>
			
			<div id="technoStackList">
				<p><strong>The Web-Development Technological stack list</strong></p>		    
			    <ul id="technoStack" class="list-group list-group-flush">	            
	            	<li id="tech1" class="list-group-item">jQuery</li>
	            	<li id="tech2" class="list-group-item">AngularJs</li>
	            	<li id="tech3" class="list-group-item">HTML/CSS</li>
	            	<li id="tech4" class="list-group-item">JavaScript</li>
	            	<li id="tech5" class="list-group-item">NodeJs</li>
	        	</ul>
			</div>			
			
			<div id="end_message">
			    <h4 class="text-primary text-align">Thank you for your visit. Have a great day! ☺</h4>
			</div>
	    </div>
	</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.

jQuery Traversing - Deploy Application on Tomcat
Fig. 7: 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.

http://localhost:8082/jQueryTraversing/

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

jQuery Traversing - Index page
Fig. 8: Index page

Users can click buttons to display the result of the different jQuery traversal methods. That is all for this tutorial and I hope the article served you whatever you were looking for. Happy Learning and don’t forget to share!

6. Conclusion

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

7. Download the Eclipse Project

This was an example of jQuery Traversing Methods.

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

Yatin

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.
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