An extensible command line interface for the browser.

This project explored creating a command line interface that runs in the browser, combining two types of interfaces into a unique user experience. The application was written in Dart, a language developed by Google that transpiles to JavaScript to run in the browser.

The hardest part of the project was, of course, trying to replicate a bash command line with process management. For it to be useful to users at all, it needed to provide core functionality that users expect from a command line. Scope creep started to slow down development momentum, so eventually I had to nail down what features I wanted in release v1.0.0 and settle for additional features in later releases. The desired functionality for the first release was as follows:

• Interactive IO
• Process management
• Environment variable storage, recall, and persistence
• Command completion (via the tab key)
• Input history (accessible with the up and down keys)
• A set of standard library processes

The set of standard library processes in v1.0.0 includes:

authentication

loads user/session information from the document cookies and (in later versions) will authenticate the user’s credentials.

echo

prints the supplied input back to the shell.

export

creates a variable that persists across browser sessions via cookies.

help

offers help information for the command line interface.

jobs

lists all processes that are currently running.

printenv

prints all environment variables.

testinput

demonstrates how to get user input from within a process and how to call other commands from within a process.

unset

erases an environment variable.