brainfuck.js

var args = message.getContent().split(" ");
if (args.length == 1) {
    channel.message("$brainfuck <code> [ \"|\" <input> ]");
    return;
}

args = args.slice(1).join(" ");
var brainfuck;
var input;
if (args.contains("|")) {
    args = args.split("|");
    brainfuck = args[0];
    input = args.slice(1).join("|").trim().split(" ");
} else {
    brainfuck = args;
    input = "";
}
var ascii = false;
for (var i = 0; i < input.length; i++) {
    if (isNaN(input[i]) || +input[i] % 1 != 0 || +input[i] < 0 || +input[i] >= 256) {
        ascii = true;
        break;
    }
}
if (ascii) {
    input = input.join(" ").split("");
    for (var i = 0; i < input.length; i++) {
        input[i] = input[i].charCodeAt(0) % 256;
    }
} else {
    for (var i = 0; i < input.length; i++) {
        input[i] = +input[i];
    }
}

var pc = 0;
var ptr = 0;
var inputIndex = 0;
var mem = []
var stack = [];
var output = [];
var zeroIdx = 0;

function adjustIndex(idx) {
    if (idx < 0) {
        mem.unshift(0);
        idx++;
        zeroIdx--;
    } else while (idx >= mem.length) {
        mem.push(0);
    }
    return idx;
}

programLoop:
while (pc != brainfuck.length) {
    var ch = brainfuck[pc];
    switch (ch) {
        case ">":
            ptr++;
            break;
        case "<":
            ptr--;
            break;
        case "+":
            ptr = adjustIndex(ptr);
            mem[ptr] = mem[ptr] == 255 ? 0 : mem[ptr] + 1;
            break;
        case "-":
            ptr = adjustIndex(ptr);
            mem[ptr] = mem[ptr] == 0 ? 255 : mem[ptr] - 1;
            break;
        case ".":
            ptr = adjustIndex(ptr);
            output.push(mem[ptr]);
            break;
        case ",":
            var val;
            if (inputIndex >= input.length) {
                val = 0;
            } else {
                val = input[inputIndex];
                inputIndex++;
            }
            ptr = adjustIndex(ptr);
            mem[ptr] = val;
            break;
        case "[":
            ptr = adjustIndex(ptr);
            if (mem[ptr] != 0) {
                stack.push(pc);
            } else {
                var bracketCount = 1;
                while (bracketCount > 0) {
                    pc++;
                    if (pc == brainfuck.length) {
                        channel.message("Unbalanced [] square brackets");
                        stack = [];
                        break programLoop;
                    }
                    if (brainfuck[pc] == "[")
                        bracketCount++;
                    else if (brainfuck[pc] == "]")
                        bracketCount--;
                }
            }
            break;
        case "]":
            if (stack.length == 0) {
                channel.message("Unbalanced [] square brackets");
                break programLoop;
            }
            pc = stack.pop() - 1;
            break;
        case "?":
            var indices = "";
            var values = "";
            for (var i = 0; i < mem.length; i++) {
                var ind = "" + (i + zeroIdx);
                var val = "" + mem[i];
                while (ind.length < val.length)
                    ind = " " + ind;
                while (val.length < ind.length)
                    val = " " + val;
                if (indices.length != 0)
                    indices += " ";
                indices += ind;
                if (values.length != 0)
                    values += " ";
                values += val;
            }
            channel.message("```\nIndices: " + indices + "\nValues:  " + values + "\n```");
            break;
    }
    pc++;
}

if (stack.length != 0)
    channel.message("Unbalanced [] square brackets");

if (output.length == 0) {
    channel.message("Program terminated with no output");
} else {
    channel.message(output.join(", "));
    for (var i = 0; i < output.length; i++)
        output[i] = output[i] <= 32 ? " " : String.fromCharCode(output[i]);
    channel.message(output.join(""));
}