Simple function for creating element that rotate based on the mouse position. In other words, the element is looking-at/following the mouse.

rotateElement.js

/**
 * DEMO: https://jsfiddle.net/gd6b71Ln/38/
 *
 * CAUTION: You will need to edit `el.style.transform = 'rotate('+ deg +'deg)'`, 
 *          in case the element has already existing transform styles (just append them)
 *
 * COMPATIBILITY: https://caniuse.com/#feat=getboundingclientrect
 *                https://caniuse.com/#feat=transforms2d
 *
 * Makes the element rotate based on the mouse position
 * @param {HTMLElement} el - Element that is going to be rotated
 * @return {undefined}
 */
function followMouse (el) {
    const position = el.getBoundingClientRect();
    const callback = function(event) {
        const x = event.x - (position.x + position.width / 2);
        const y = position.y + position.height / 2 - event.y;
        const degrees = Math.atan(x / y) * (180 / Math.PI) + (y < 0 ? 180 : 0);
        el.style.transform = `rotate(${degrees}deg)`;
    };
    document.addEventListener('mousemove', callback, true);
}