Befunge93

Befunge93 is an interpreter written in JavaScript for the Befunge93 esoteric programming language.

Installation

Befunge93 is available on npm!

npm install befunge93

Getting started

To run a Befunge program, just create a new interpreter and call #run with your program as the argument.

#run returns a promise that is resolved when the program terminates (by parsing a "@").

const Befunge = require('befunge93');
let befunge = new Befunge();
 
befunge.run("1234v\n>9 #5>:#._@\n^876<")
    .then((output) => {
        console.log(output);
    });

Outputs: "9 8 7 6 5 4 3 2 1 "

Advanced Usage

Befunge93 provides you with a few callbacks to hook into the interpreter.

In order to provide the interpreter with input/output, you must supply the #onInput and #onOutput callbacks.

#onInput

Called when the interpreter needs input from the user. Ie. the ~ and & commands.
Example:

befunge.onInput = (message) => {
    return prompt(message);
};

#onOutput

Called when the interpreter outputs a character. Ie. the , and . commands
Example:

befunge.onOutput = (output) => {
    console.log(output);
};

#onStep

Called when the program's cursor changes.
Example:

befunge.onStep = (x, y) => {
    console.log(`Current x position: ${x}`);
    console.log(`Current y position: ${y}`);
};

#onStackChange

Called when the stack is updated.
Example:

befunge.onStackChange = (stack) => {
    console.log(`Current stack: ${stack.toString()}`);
};

#onCellChange

Called when a cell is updated by the p command.
Example:

befunge.onCellChange = (x, y, newValue) => {
    console.log(`Cell at ${x}, ${y} has been updated to ${newValue.toString()}`);
};