Ask HN: Most interesting tech you built for just yourself?

//@ts-check window.kVideoSpeed = 1; window.initialVolume = 1;

NUMPAD_3 = "99" NUMPAD_2 = "98" NUMPAD_6 = "102" NUMPAD_5 = "101"

UP_ARROW = "38" DOWN_ARROW = "40"

let timeoutId = null; document.onkeydown = (e) => { if (!document.querySelectorAll("video").length) { // no-op for pages with no videos return; } window.initialVolume = document.querySelector('video')?.volume || 1

    let myDiv = getOrMakeDiv();
    e = e || window.event;
    let KEYCODE = e.keyCode;

    // NOTE: can't use left/right b/c those go forward/back 10s on some sites
    if ((KEYCODE == UP_ARROW || KEYCODE == NUMPAD_6) && window.kVideoSpeed  1) {
        // down arrow
        window.kVideoSpeed -= 0.5;
        myDiv.textContent = window.kVideoSpeed;
    }
    for (let el of document.querySelectorAll("video")) {
        el.playbackRate = window.kVideoSpeed;

        // prevent volume from changing
        setTimeout(() => {
            el.volume = window.initialVolume
        }, 100)
    }
    if (timeoutId) {
        clearTimeout(timeoutId);
    }
    // set timeout to remove div
    timeoutId = setTimeout(() => { myDiv.remove() }, 1000);

        let div = document.createElement("div");
        div.id = "myDiv";
        // add styles to div
        div.style.padding = "8px";
        div.style.textAlign = "center";
        div.style.fontSize = "16px";
        div.style.position = "fixed";
        div.style.fontWeight = "600";
        div.style.border = "1px solid yellow";
        div.style.color = "white";
        div.style.backgroundColor = "black";
        div.style.zIndex = "999999";
        // insert div at the top of the body
        if (document.fullscreenElement) {
            document.fullscreenElement.prepend(div, document.fullscreenElement.firstChild)
        }
        else {
            document.body.insertBefore(div, document.body.firstChild);
        }
    }
    return document.getElementById("myDiv");
}

I was able to read in all the data points and then use the weather forecast and a few other data points to make changes to my HVAC system. The comfort different has been very drastic. Our house doesn't overheat on hot days and doesn't get cold fast when the temperature drops. (I am in the Northeast where there are big swings).