Introduction to jQuery

Section 1

What is jQuery?

jQuery is a JavaScript library that makes writing JavaScript for websites easier and more browser friendly.

jQuery is used to make your website more dynamic! Write less, do more.

jQuery: Write less, do more

How do we add the jQuery library to our site?

Before you can start coding jQuery, the library needs to be added to your site.

It should go in the head section of your HTML. Take a second to add this line of code to your site.

<script src=""></script>

What is a CDN?

A Content Delivery Network

Also called a content distribution network, is an interconnected system of cache servers that use geographical proximity as a criteria for delivering web content.

Document Ready

In order for jQuery to manipulate HTML, it needs to make sure that the HTML is fully loaded before running the jQuery.

    // jQuery code goes in here

So whenever you write jQuery, you'll need to wrap that code in a document.ready function, as shown below:


$() is a shortcut for jQuery(). The $() is made for selecting an element and then returning that element to perform an action on it.

make it rain cat

jQuery Selectors

The following code selects the element that has the ID header in the HTML.

jQuery selector

This is how you access HTML elements with jQuery. Once you have the element in the jQuery object, you can do stuff to it.

Where do we write our jQuery?

Create a new JavaScript file in Editey called main.js. Save it to your project folder.

where to put your new js file

Add the following line of code to your index.html file right BEFORE the closing </body> tag.

<script src="main.js"></script>

Enough Talk: Let's Code!

In your new main.js file, add the following jQuery:

    alert('it works!');


Just like in HTML and CSS, comments are for developers and are not interpreted by the browser.

Your code has two sets of comments. They show the two different ways of formatting comments.


One is to surround the comment by /* on one side and */ on the other. These comments can be multiple lines long.

            /* This comment
            is three
            lines long. */

Two is to have // before the comment. This kind of comment can only be one line long.

            // This comment is only one line long.

jQuery Plugins

Don't Reinvent the Wheel

Because jQuery is widely used, a lot of people have created jQuery code(plugins) that you can download and easily add to your own site.

trike with a square front wheel

image source

Using jQuery Plugins on Your Site

jQuery plugins will come with an external file that you will need to download and reference in your site. Then you 'initialize' their jQuery by connecting it to one of your own HTML elements.

t-rex trying to plug in a cord

Real world example: Slideshow

Now we're going to step through together how to add a slideshow jQuery plugin.

Start by Googling 'Owl Slider' or go to:

Enough Talk: Let's Code!

Add the file references to your HTML

In the head tag section of your HTML, add these 2 stylesheets:

<link rel="stylesheet" type="text/css" href="" />
<link rel="stylesheet" type="text/css" href="" />

AFTER your jQuery script tag in the head tag of your project, add the following:

<script src=""></script>

Enough Talk: Let's Code!

Setup Your HTML Markup

In your HTML, add the following HTML where you want your slider to appear.

<div class="owl-carousel owl-theme slideshow">

Enough Talk: Let's Code!

Add in your Slider Images

Download 3 images from the internet and put them in your project folder.

Each time it says 'Content' in the HTML, replace the word Content with an img tag.

<div class="owl-carousel owl-theme slideshow">
  <div><img src="captain.png" /></div>
  <div><img src="hyperlink.png" /></div>
  <div><img src="cape.png" /></div>

Initialize your jQuery slider

In your main.js file, add the following code:

/* Get The Document Ready! */

    // Owl Slider
        item: 1


jQuery Functions

Funtions are a way of reusing code in JavaScript.

The .owlCarousel function lets you reuse all the owl carousel code to create a slider.

.owlCarousel calls the owl carousel function

jQuery Options

jQuery plugins have options which allow you to customize the way the plugin works and displays on the page.

The plugin documentation explains what options there are and what values you can put in them. Sometimes the documentation refers to options as settings.

Owl slider documentation on its options.

Enough Talk: Let's Code!

Explore the Owl Slider options and update your slider.

I meant to behave but there were too many options



Add one of these jQuery Plugins to your site:

Get some hints on the homework page.


sheep have many questions