@pexip/signal/dist/buffer.js

an observer pattern while avoiding boilerplate code. https://en.wikipedia.org/wiki/Signals_and_slots

export const createBuffer = (size) => {
    const buffer = new Array();
    return {
        [Symbol.iterator]: () => buffer[Symbol.iterator](),
        get size() {
            return buffer.length;
        },
        add: value => {
            if (size === 0) {
                return;
            }
            if (buffer.length < size) {
                buffer.splice(size, 0, value);
            }
            else {
                buffer.shift();
                buffer.push(value);
            }
        },
        clear: () => {
            buffer.length = 0;
        },
        entries: () => buffer.entries(),
    };
};