Return Promise if callback is not provided?

Nice to have in ES2017 async/await development

const asyncjs = require('async');
const foo = async () => {
    const arr = Array.from({ length: 1000 }, (v, i) => i);
    const transformedArr = await asyncjs.mapLimit(arr, 100, async (v) => {
        return await Promise.resolve(v * 2);
    });
    console.log(transformedArr);
}

[aearly]

I’ve thought about this, and experimented with it a bit. People are going to want to await Async.mapLimit(arr, 10, async foo => {...}). It could very well be something we include in 3.0.

Also, some Async methods would be pretty silly with async/await, e.g. series, waterfall.

[ex1st]

@tritoanst, your promisify function is overhead. It may be easier:

function promisify(original) {
	return function (...args) {
		return new Promise((resolve, reject) => {
			args.push((err, result) => {
				if (err) {
					reject(err);
				} else {
					resolve(result);
				}
			});

			original.apply(this, args);
		});
	};
}

const foo = async () => {
    const arr = Array.from({ length: 1000 }, (v, i) => i);
    const transformedArr = await promisify(async.mapLimit)(arr, 100, async (v) => {
        return v * 2; // `return await` is redundant
    });
    console.log(transformedArr);
};