web222

WEB222 - Week 5

Suggested Readings

Running a Development Web Environment

Developing for the web requires at least 3 things pieces of software:

  1. a proper code editor which, is aware of HTML, JavaScript, and CSS
  2. a web client (i.e., browser), with developer and debugging tools
  3. a web server, to serve your web pages over HTTP to a browser

Code Editor

For our code editor, we will be using Visual Studio Code, which is a free (open source) code editor created and maintained by Microsoft. It also works on Windows, macOS, and Linux. Make sure you have downloaded and installed it on all the computers you will use for web development.

Web Client

For our web client we will use the many web browsers we introduced in Week 1, namely:

There are many more, and you are highly encouraged to install as many as possible.

Web Server

We will also need a web server to host our web pages and applications. Installing and running a web server can be complicated. Industry-grade web servers like Apache and nginx are free and can be installed and run on your local computer; however, they are much more complicated and powerful than anything we will need for hosting our initial web pages.

For our purposes, we will use one of the many simple node.js based HTTP servers. In order to use them, do the following:

  1. Make sure you have installed node.js on your computer.
  2. In a terminal window, navigate to the directory that you want your web server to host. For example cd my-website
  3. Now download and run a web server using the npx command.

For example, you can use the serve web server like this:

cd my-website
npx serve
Need to install the following packages:
  serve@14.2.1
Ok to proceed? (y)

   ┌──────────────────────────────────────────┐
   │                                          │
   │   Serving!                               │
   │                                          │
   │   - Local:    http://localhost:3000      │
   │   - Network:  http://10.7.133.229:3000   │
   │                                          │
   │   Copied local address to clipboard!     │
   │                                          │
   └──────────────────────────────────────────┘

You can now open your web browser to http://localhost:3000 and browser your files. This uses the http protocol, and connects you to the special IP address 127.0.0.1, also known as localhost (i.e., you can also use http://localhost:3000). The localhost IP address always refers to this computer, and allows you to connect network clients to your own machine. The final :3000 portion of the URL is a port number. Together, http://127.0.0.1:3000 means connect using HTTP to my local computer on port 3000.

NOTE: the second External IP address will be different than the above, but 127.0.0.1 will always be correct.

When you are done testing your web site, stop the web server by pressing CTRL-C in your terminal window. To run the server again, use npx serve.

HTML

HTML is the HyperText Markup Language. It allows us to write content in a document, just as we would in a file created by a word processor. Unlike a regular text file, it also includes structural and layout information about this content. We literally mark up the text of our document with extra information.

When talking about HTML’s markup, we’ll often refer to the following terms:

HTML Document

The first HTML page ever created was built by Tim Berners-Lee on August 6, 1991.

Since then, the web has gone through many versions:

Basic HTML5 Document

Here’s a basic HTML5 web page:

<!doctype html>
<html>
    <head>
        <meta charset="utf-8">
        <title>My Web Page</title>
    </head>

    <body>
        <!-- This is a comment -->
        <h1>Hello World!</h1>
    </body>
</html>

Let’s break this down and look at what’s happening.

  1. <!doctype html> tells the browser what kind of document this is (HTML5), and how to interpret/render it
  2. <html> the root element of our document: all other elements will be included within <html>...</html>.
  3. <head> provides various information about the document as opposed to providing its content. This is metadata that describes the document to search engines, web browsers, and other tools.
  4. <meta> an example of metadata, in this case defining the character set used in the document: utf-8
  5. <title> an example of a specific (named) metadata element: the document’s title, shown in the browser’s title bar. There are a number of specific named metadata elements like this.
  6. <body> the content of the document is contained within <body>...</body>.
  7. <!-- ... --> a comment, similar to using /* ... */ in C or JavaScript
  8. <h1> a heading element (there are headings 1 through 6), which is a title or sub-title in a document.

Now let’s try creating and loading this file in our browser:

  1. Make a directory on your computer called my-website
  2. Create a new file in my-website named index.html (the index.html name is important, as it represents the main entry point to a directory of HTML files and other web resources)
  3. Use Visual Studio Code to open your my-website/index.html file
  4. Copy the HTML we just discussed above, and paste it into your editor
  5. Save your index.html file
  6. In a terminal, navigate to your my-website directory
  7. Start a web server by typing npx serve (you must do this from within the my-website directory)
  8. Open your web browser (Chrome, Firefox, etc) and enter http://localhost:3000 in the URL bar
  9. Make sure you can see a new page with Hello World! in black text.

Now let’s make a change to our document:

  1. Go back to your editor and change the index.html file so that instead of Hello World! you have This is my web page.
  2. Save your index.html file.
  3. Go back to your browser and hit the Refresh button.
  4. Make sure your web page now says This is my web page.

Every time we update anything in our web page, we have to refresh the web page in our browser. The web server will serve the most recent version of the file on disk when it is requested. Web browsers and servers disconnect from one another after processing a request/response.

Common HTML Elements

There are many HTML elements you’ll learn and use, but the following is a good initial set to get you started.

You can see an example page that uses every HTML element here.

Metadata

Information about the document vs. the document’s content goes in various metadata elements:

Major Document Sections

Content Sections

These are organizational blocks within the document, helping give structure to the content and provide clues to browsers, screen readers, and other software about how to present the content:

Text Content

We organize content into “boxes,” some of which have unique layout characteristics.

Inline Text

We also use elements within larger text content to indicate that certain words or phrases are to be shown differently:

Multimedia

In addition to text, HTML5 also defines a number of rich media elements:

Scripting

We create dynamic web content and applications through the use of scripting:

Examples

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