Async plugins

[TrySound]

Is there a way to use asynchronous in plugins? rollup could detect promise returned from plugin like

export default function string (opts) {
    return {
        transform (code, id) {
            if (filter(id)) {
                if (opts.someAsyncOpt) {
                    return new Promise(function (code) {
                        resolve(code);
                    });
                }
                return code;
            }
        }
    };
}

[Rich-Harris]

It could be done, certainly. There's a slight performance penalty associated with async-ifying transforms since you basically need to wrap everything in a Promise.resolve() – do you have a specific use case in mind?

[TrySound]

@Rich-Harris https://github.com/JohnPostlethwait/stringify accepts minificators for code. It make sense in browser. But minificators api can be async (cssnano is async)