Download the files

• Open the extensions project on replit.
• You should see an images directory, a docs directory and the files manifest.json, README.md, tab.css, index.html, and tab.js.

Modify the HTML

• We will look at the code in index.html as a class.
• Locate an image to use on the page (less than 50KB) and download it into the images directory.
• Once you understand the html, you may start editing the file to incorporate your own links for this page.
• Edit the img tag to reference the image you downloaded.
• Once you have the links you want and the image, we'll move on to the style sheet.

Modify the CSS

• We will look at the code in tab.css as a class.
• Modify tab.css by changing the declarations of .links, .caption, #clockbox, elements or any other selector found within.
• Be sure to frequently run index.html to see the results of any changes.

Make an icon

• Go to favicon.io to make an icon.
  
• Make an icon with your initial, like the one here:
• When you download your design, it creates a zip file containing a directory of various sizes of the image. Since we're using an existing template, we're going to make our images fit the current structure.
• Open up the favicon.ico file in an image editor (preview or gimp or windows equivalent).
• Export your icon image multiple times with multiple sizes:
  • An image of size 128x128 to a file named 128x128.png
  • An image as 72x72 to a file named e_small.jpg
  • An image as 72x72 to a file named rsz_n60-2stack-w_small.png

JSON

• We will step through the JSON powerpoint slides found here: JSON.pptx
• Open the manifest.json file.
• Modify the items noted in red below to customize your extension.

          {
          "manifest_version": 2,
          "name": "Custom Web Launcher",
          "short_name": "Web Launch",
          "version": "0.4",
          "description": "A Chrome new tab extension that can be customized
          each semester. Learn how at the SIGCSE 2018 Chrome Home Workshop.",
          "icons": {
          "128": "images/128x128.png"
          },
          "browser_action": {
          "default_icon": {
          "16": "images/rsz_n602stackw_
          small.png"
          },
          "default_title": "Custom Web Launcher"
          },
          "author": "Denise Case and Doug Hawley",
          "chrome_url_overrides": {
          "newtab": "tab.html"
          },
          }
                

• Save manifest.json

Javascript

We will step through the JavaScript powerpoint slides found here: JS.pptx

1. Add a background image to your page
   • Find a background image you like.
   • In index.html, add a static background image by changing <div id="background"> to <div id="background" style="background-image:url(http://bing.com//az/hprichbg/rb/HuangshanClouds_EN-US9460330019_1920x1080.jpg)"> where the url of your desired image is located in the parentheses after url
2. Style your background image with CSS
   • In your tab.css file, set style for element with id="background" to the following (or vary it as you like).

         #background {
           height: 100%;
           opacity: 1.00;
           background-position: center;
           background-repeat: no-repeat;
           background-size: cover;
         }
                     

3. Call your new function when the window is created
   • Update the handler for windows.onload to call a function that will update the background image. We will add the function UpdateBackgroundImage in the next section.
   • To do this, locate the window.onload function at the bottom of the file tab.js. You will add the call to UpdateBackgroundImage so that your window.onload function now appears as follows:

         window.onload = function () {
           UpdateBackgroundImage('https://www.bing.com/HPImageArchive.aspx?format=js&idx=0&n=1')
           GetClock()
           setInterval(GetClock, 1000)
           GetGreeting()
           setInterval(GetGreeting, 1000)
         }

4. Add three new functions
   • Still in tab.js, add the new update function and the two helper functions to the end of your JavaScript file.

         /**
         * Update background image with Bing Image of the Day
         * @param {String} url
         */
         function UpdateBackgroundImage(url) {
           let xmlhttp = new window.XMLHttpRequest()
           xmlhttp.onreadystatechange = function () {
           if (this.readyState == 4 && this.status == 200) { // when done & successful
             console.log('Response received: ' + this.responseText)
             var imageURL = ExtractImageURL(JSON.parse(this.responseText));
             console.log('Image url: ' + imageURL)
             SetBackgroundImage(imageURL)
             }
           };
           xmlhttp.open("GET", url, true) // define the request as a get, to this url, asynchronous
           xmlhttp.send() // actually send request to server
         }
       

         /**
         * Extract first image URL from Bing response JSON.
         * @param {Object} response
         * @return {String} imageURL
         */
         function ExtractImageURL(response) {
           var suffix = response.images[0].url
           return 'http://bing.com/' + suffix
         }
       

         /**
         * Set background image to imageURL
         * @param {String} imageURL
         */
         function SetBackgroundImage(imageURL) {
           document.getElementById("background").style.backgroundImage = 'url("' + imageURL + '"'
         }

5. Bonus: Add a custom welcome message based on your schedule
   • In your index.html file, create a new HTML element with an id="welcome" just like the element with id="greeting".

         <span class="border" id="greeting"></span>
         <span class="border" id="welcome"></span>
           

   • Create a GetWelcome() function. In the function, get a new Date(). Use if statements and tday[nday] (e.g. Mon) to create a "Welcome to Web!" greeting based on your course schedule. Hint: to make it easier to read, you might write one function isMonOrWed() to which you pass nday to find out if it's a web class day, and a second function to determine if the time is between 3:00pm and 4:00pm.

           let result = false
           if (tday[nday] === 'Mon' || tday[nday] === 'Wed') {result = true}
           return result
         

Deploying your extension

The purpose of this section is to provide an overview of how to deploy a custom Chrome new tab extension to the Chrome store.

1. Slides about deployment: Deploy.pptx
2. Ensure that you have the three images created above stored in the images folder:
   • An image of size 128x128 to a file named 128x128.png
   • An image as 72x72 to a file named e_small.jpg
   • An image as 72x72 to a file named rsz_n60-2stack-w_small.png
3. Verify manifest.json
   • Make sure your manifest.json is correct for this version (you can use version 0.0.1 for your first upload, and will increment each updated version after that).
   • Check the following fields:
     • name
     • short_name
     • version (recommended: 0.0.1 for the initial release)
     • description
     • browser_action - make sure it points to your new png files and includes a helpful tooltip.
     • author
     • make sure index.html is referring to your current index.html file
4. Test it locally
   • Download all the files into a directory on your computer.
   • From that directory, right-click index.html and open it in chrome.
   • Use the developer options to open your unpacked project.
     • Go to "More Tools -> Extensions" in browser
     • Choose "load unpacked" and navigate to your working app folder
       
     • Open a new tab in Chrome and you should see your page.
5. Optional: Zip/pack your project for publishing
   Disclaimer: I have not published my web launcher, so I am just relaying the information I was given for this section. I have had no problem using my extension by keeping the app directory on a shared drive such as google drive or dropbox that is accessible from all my computers. Once the extension is installed on a computer's Chrome browser, it will access the copy that is in the shared drive.
   • Be sure to include the following in your zipfile:
     • index.html
     • tab.css
     • tab.js
     • manifest.json
     • images folder
6. Optional: Publish it
   Disclaimer: I have not published my web launcher, so I am just relaying the information I was given for this section. I have had no problem using my extension by keeping the app directory on a shared drive such as google drive or dropbox that is accessible from all my computers. Once the extension is installed on a computer's Chrome browser, it will access the copy that is in the shared drive.
   • Create a new gmail just for this app
   • Register and pay for a Google developer account($25)
   • Go to your Google Developer Dashboard and add new item (upload your zip file - $5)