@specialblend/unpromisify/dist/index.esm.js

convert async functions into callback style functions

import assert from 'assert';

function unpromisify(handler) {
    return (...args) => {
        assert(args.length, 'unpromisified handler needs at least 1 argument');
        const params = args;
        const callback = args.pop();
        assert(typeof callback === 'function', 'provided callback argument must be a function');
        handler(...params)
            .then(data => callback(null, data))
            .catch(callback);
    };
}

export default unpromisify;