bot-commands.js

import vm from 'vm';

export default {

    [ '>' ] (input) {
        const context = {
            Array,
            Boolean,
            Buffer,
            Date,
            Map,
            Math,
            Number,
            Object,
            Promise,
            RegExp,
            Set,
            String,
            Symbol,
            WeakMap,
            WeakSet,
            setTimeout
        };
        
        const result = vm.runInNewContext(input, context, { timeout: 10000 });

        return `Eval: **\`${ JSON.stringify(result) }\`**`;
    },

    math (input) {
        let expression = input.replace(/\s/g, '');

        const numbers = /((?:\d|\.)+)/;
        const groups = /\((.+?)\)/;
        const methods = [
            { op: /((?:\^|\*\*))/, fn (x, o, y) { return Math.pow(x, y) } },
            { op: /(\*|\/|\%)/, fn (x, o, y) {
                switch (o) {
                    case '*': return x * y;
                    case '/': return x / y;
                    case '%': return x % y;
                }
            } },
            { op: /(\+)/, fn (x, o, y) { return x + y } },
            { op: /(\-)/, fn (x, o, y) { return x - y } }
        ];

        const evaluate = terms => {

            for (const { op, fn } of methods) {
                const regex = new RegExp(numbers.source + op.source + numbers.source);

                while (terms.match(regex)) {
                    const [ term, x, o, y ] = terms.match(regex);
                    terms = terms.replace(term, fn(Number(x), o, Number(y)));
                }
            }

            return terms;
        }

        while (expression.match(groups)) {
            const [ group, terms ] = expression.match(groups);
            expression = expression.replace(group, evaluate(terms));
        }

        return `Math: **\`${ evaluate(expression) }\`**`;
    }
}