Reddit Sentiment Analyzer is a Chrome extension that augments Reddit viewing experience by scoring each Reddit comment's sentiment polarity (positive/negative) using VADER, a lexicon and rule-bases sentiment analysis tool.

The score ranges from -1.0 to 1.0 and would appear in a banner above each comment. The banner would have different background and foreground colors depending on the score. There are 5 different sets of colors for the following 5 sentiments.

All the colors are customizable. There is also an on/off toggle that controls whether the extension is enabled.

To install the extension in Chrome, you can:

• Clone the Git repo to your desired location.
• Navigate to chrome:https://extensions/ in Chrome.
• Turn on "Developer mode" (controlled by the toggle on the upper right).
• Click "Load unpacked" and load the extension folder in the cloned Git repo.
• You should now see Reddit Sentiment Analyzer in your extension tray. You can pin it if you want.

Once you have the extension installed, you can go to Reddit where you should see the sentiment scores in the Reddit comment pages. You can configure the colors and toggle the extension on and off in the extension popup.

The extension uses a JavaScript port of VADER, vaderSentiment-js, to score the Reddit comments. To use the npm package inside a browser extension, Browserify is employed to bundle the package inside a JavaScript file: bunlde.js, which can be loaded into the web pages when needed.

The steps to generate the bunlde.js are as follows:

• Download and install node.js and npm. (Instructions can be found here.)
• Install Browserify: npm install -g browserify.
• Inside the nodejs folder, run make, which should invoke the instructions in the Makefile to "browserify" vaderSentiment-js. (If you are on a platform that does not support make, just run the command in the Makefile.)

Implementation of the extension itself can be found in the extension folder, which can be loaded as an unpacked extension in Chrome once you have "Developer mode" enabled.

The manifest.json is the Chrome extension manifest file. It ties the files in the unpacked extension together and tells Chrome what each file does.

The popup.html and popup.js are for the extension popup. When you have the extension installed and click its icon in your Chrome extension tray, you will see the popup where you can configure the background and the foreground colors for each of the 5 sentiments and toggle the extension on and off. The configurations (the extension state) are persisted using chrome.storage.

The bundle.js and content.js are loaded into each page that matches the url filter defined in the manifest. The bundle packages the JavaScript port of VADER which is used in the content script to score the comments. The content script finds the comments inside a Reddit page using query selectors, scores them, and displays them as configured.

The background.js initializes the extension on install and listens for tab updates so that it sends a message to the content script if the tab updated is a Reddit comment page. The content script only starts looking for comments and score them when messaged by the background script. When the extension is toggled off, the background script will stop sending messages to the content script.

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