• 20 hours
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Last updated on 8/5/19

Understand HTTP, AJAX, and JSON

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Put your acronym helmet on! We're about to see a few tools that govern requests and responses over the web. This is mostly a theory chapter; no code.


HTTP stands for Hyptertext Transfer Protocol. You're using HTTP all the time on the web. Take a look up at your browser's address bar, where you see openclassrooms.com. See how it's preceded by https? This means HTTPS (the secure version of HTTP) is the protocol you're currently using!


Protocols are a defined system for sending information. HTTP works on a client/server model, meaning you have a client on one side making a request and a server that sends back a response. 

There's plenty to say about HTTP, but let's leave it at that for now. For more information about HTTP, check out this writeup from the Mozilla Developer Network.


JSON stands for JavaScript Object Notation. It's a data structure!

Code will often receive data in JSON, process it (also called parsing), and use it somehow, whether it displays the data or does something with it behind-the-scenes.

Here's an example of a candy list written in JSON that we'll use later in the course.

        "name": "Gummies",
        "brand": "Haribo",
        "quantity": 5
        "name": "Chocolate",
        "brand": "Hershey's",
        "quantity": 3
        "name": "Licorice",
        "brand": "Twizzlers",
        "quantity": 4
        "name": "Truffles",
        "brand": "Godiva",
        "quantity": 0


AJAX stands for Asynchronous JavaScript and XML. In traditional HTTP situations, your browser loads a page that it receives from a server. For example, when you submit a form, your page usually refreshes to show a new page that confirms the information was submitted. 

With AJAX, however, you can update a page without reloading it entirely. Think about your experiences on Facebook or Gmail; you use the interface without the entire page reloading every time you add a comment or click on an email. That's AJAX in all its glory!

Example of certificate of achievement
Example of certificate of achievement