I usually do not create Streams, but it seems that JavaScript doesn't have a built-in one and I figured I would do it for a personal project I am working on. This code seems to work as intended and does what I want just fine, but I have concerns mainly about how often I am checking my buffer. I am mainly looking for a recommendation about how often I should check to see if any data has been written to my buffer. If there are any other improvements/suggestions, I am open to hearing them!

Edit: After thinking about this more, I realized I could do this as event-driven instead and let the system/browser handle the blocking. I left both functions in so people can weigh in on either one. However, I would still like input on the first approach for general knowledge.

const dataAddedEvent = new Event('stream.data_recieved');
const dataAddedEventTarget = new EventTarget();

const StreamPrototype = {
    _data: [],
    _callbacks: [],

readAsync: async function* () {
    while(await sleep(25)) {
        let data;
        while((data = this._data.pop()))
            yield data;
    }
},

onData: function(callback) {
    if (callback instanceof Function)
    this._callbacks.push(callback);
},

push: function(data) {
    if (data) {
        this._data.push(data);
        this._callbacks.forEach(item => {
            item(data);
        });
    }
}

};

// This was just copied from the internet
const sleep = time => new Promise(res => setTimeout(res, time, "done sleeping"));