Discussion on: Vanilla JS SlideDown/Up

[kartofelek007]

with and without box-sizing:

let slideUp = (target, duration=500) => {
    target.style.transitionProperty = 'height, margin, padding';
    target.style.transitionDuration = duration + 'ms';
    const computed = getComputedStyle(target);
    if (computed.boxSizing === "border-box") {
        target.style.height = target.offsetHeight + 'px';
    } else {
        const pt = parseFloat(computed.paddingTop);
        const pb = parseFloat(computed.paddingBottom);
        const bt = parseFloat(computed.borderTopWidth);
        const bb = parseFloat(computed.borderBottomWidth);
        target.style.height = target.offsetHeight - pt - pb - bt - bb + 'px';
    }
....