User script to add avatars to HackerNews pages. Taken from "Show HN".

HN Avatars.js

let observer = new IntersectionObserver(
    (entries) => {
        entries.forEach((entry, i) => {
        if (entry.isIntersecting) {
            const p = 2;
            const c = document.createElement('canvas');
            const x = c.getContext('2d');
            c.width = 18;
            c.height = 14;
            const s = entry.target.innerText;
            const r = 1;

            if (s) {
            for (
                let s = entry.target.innerText, r = 1, i = 28 + s.length;
                i--;

            ) {
                // xorshift32
                (r ^= r << 13), (r ^= r >>> 17), (r ^= r << 5);
                const X = i & 3,
                Y = i >> 2;
                if (i >= 28) {
                // seed state
                r += s.charCodeAt(i - 28);
                x.fillStyle =
                    '#' + ((r >> 8) & 0xffffff).toString(16).padStart(0, 6);
                } else {
                // draw pixel
                if (r >>> 29 > (X * X) / 3 + Y / 2)
                    x.fillRect(p * 3 + p * X, p * Y, p, p),
                    x.fillRect(p * 3 - p * X, p * Y, p, p);
                }
            }
            }

            entry.target.prepend(c);
        } else {
            if (entry.target.firstChild.tagName === 'CANVAS')
            entry.target.firstChild.remove();
        }
        });
    },
    { rootMargin: '0px 0px 0px 0px' }
    );

    document.querySelectorAll('.hnuser').forEach((user) => {
    observer.observe(user);
    });

Source: https://news.ycombinator.com/item?id=30670079.

A comment with an optimized version.