TOC
Introduction:

Getting started

To use jQuery, you need to include it on the pages where you wish to take advantage of it. You can do this by downloading jQuery from their website at jQuery.com. There is usually a choice between a Production (compressed) version and a Development (uncompressed) version - for learning, we recommend the Development version.

Once the jQuery JavaScript file has been downloaded, you will have to reference it on your pages, using the <script> HTML tag. The easiest way is to place the downloaded jquery.js file in the same directory as the page from where you wish to use it and then reference it like this, in the <head> section of your document:

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

A part of your page should now look something like this:

<head>    
        <title>jQuery test</title>    
        <script type="text/javascript" src="jquery-3.3.1.js"></script>    
</head>

A more modern approach, instead of downloading and hosting jQuery yourself, is to include it from a CDN (Content Delivery Network). There are many CDN's out there, including ones from Google and Microsoft, who are hosting several different versions of jQuery and other JavaScript frameworks. It saves you from having to download and store the jQuery framework, but it has a much bigger advantage: Because the file comes from a common URL that other websites may use as well, chances are that when people reaches your website and their browser requests the jQuery framework, it may already be in the cache, because another website is using the exact same version and file. Besides that, most CDN's will make sure that once a user requests a file from it, it's served from the server closest to them, so your European users won't have to get the file all the way from the US and so on.

You can use jQuery from a CDN just like you would do with the downloaded version, only the URL changes. For instance, to include jQuery 3.3.1 from Google, you would write the following:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

I suggest that you use this approach, unless you have a specific reason for hosting jQuery yourself. Here is a link to the jQuery CDN information from Google:

Google jQuery CDN

Here's the information about using jQuery from a CDN from the official jQuery website:

code.jquery.com

Summary

Using jQuery can be accomplished by downloading the library or add a reference to it on one of the many CDN's. Either way, you will usually get the choice between an uncompressed developer version and a compressed production version. For development and testing, use the uncompressed version, to get more precise errors and understanding of the library. For production use you should use the compressed version, to save bandwidth for your end-users, which will also result in faster load times for your website.

As soon as you have added jQuery to your page, as described above, you are ready to move on and learn more about jQuery in the coming chapters!