Web App Development with Google Apps Script/Why GAS

Javascript everywhere
Using is nice because it's javascript on both the front and backend. Normally we expect javascript and html on the front end (meaning how our users will interact with our tool) but often you have to learn and use a different language on the backend, where you interact with your data and figure out what you need to show your users. Backend software examples include PHP, Ruby, and interesting flavors of javascript like node.js. With you do the same sort of programming everywhere.

Web editing
With can do all your editing in a browser. Your scripts are either tied to a spreadsheet or they're stand alone scripts in your Google Drive. Either way you launch the editor through drive and you get a decent, if not fantastic, development environment that you can use on a Chromebook.

Most other web development approaches encourage you to code locally on your own machine and then push your code to the server that hosts the web page. Many people use GitHub to help facilitate the pushing, but getting a nice coding environment on your local computer can be a hassle so it's nice with that you can just grab any web-connected computer to do your work.

Spreadsheets as database
What I'll be talking about mostly in this book is using simple Google Sheets to store all your data. I've done a lot of web app development using a mysql-type backend database, and I really appreciate the speed and utilities those provide. But they're a pain to set up and they're a pain to interact with separately from your web application. Google Sheets, on the other hand, are quite easy to set up and have a great user interface already for you to go look at and mess with your data.

User authentication
Assuming you're in a situation where you're programming in a Google environment (like a Google school like mine where all emails are just rebranded gmail accounts) there's a very simple command to determine the user's email address and from there you can decide what you want them to have access to.