Introduction What's a URL Shortener? URL shortening is a technique to convert a long URL (site or page address) to a shorter version. This shorter version of the URL is usually cleaner and easier to share or remember. When someone accesses the shortened address, the browser redirects to the original (large) url address. It is also called URL redirection or URL redirect.

For example, the large version of this url: http://en.wikipedia.org/wiki/URL_shortening

Can be shortened with bit.do service to this small address, that redirects to the previous longer address: http://bit.do/urlwiki

How does it work? Essentially, your database has 3 fields: primaryKey, shortCode and targetURL.

Normally the shortCode is simply the primaryKey (which is an int) converted to another base. So for instance base 36 (so 0 through 9, and then 'a' through 'z').

This makes it easy to look up the targetURL in the database, since you can just decode it to base 10 and find the primary key.

You will also have short URLs since the number of URLs you can have is 36^n where n is the number of characters in the shortened URL. So you can see that just with 4 letters you can have a possible of 2,313,441 different URLs. If you use capital letters (a larger base), this gets even larger.

node-es6-url-shortener/
│
├── api/
│   ├── controllers/
│   │   └── UrlController.js
│   │
│   ├── models/
│   │   └── Url.js
│   │
│   └── helpers/
│      └── base58.js
│
├── config/
│   ├── env/
│   │   ├── development.js
│   │   ├── index.js
│   │   ├── production.js
│   │   └── test.js
│   │
│   ├── routes/
│   │   ├── index.js
│   │   └── url.js
│   │
│   ├── express.js
│   └── sequelize.js
│
├── view/
│   ├── css/
│   │   └── styles.css
│   │
│   ├── javascript/
│   │   └── shorten.js
│   │
│   └── index.html
│
├── test/
│   └── url.test.js
│
├── .eslintrc                     * ESLint configuration file
├── .gitignore                    * Example git ignore file
├── index.mjs                     * Entry point of our Node's app
├── LICENSE                       * MIT License
├── package.json                  * Defines our JavaScript dependencies
├── package-lock.json             * Defines our exact JavaScript dependencies tree
└── README.md                     * This file

5. Install NPM dependencies

$ npm install