Calculating the angle for rotating an Element around its center

rotationByMouseMovement.js

//module ...

/**
     * rotates rotationTarget around its center point depending on the mouse position
     * CTRL key must be pressed
     *
     * trigonometry powers, activate!
     *
     * @param event MouseEvent
     */
    const mouseRotateListener = (event) => {
        if(!event.ctrlKey) {
            return;
        }

        const rect = rotationTarget.getBoundingClientRect();
        const originX = rect.left + rect.width / 2;
        const originY = rect.top + rect.height / 2;

        const adjacent = event.clientX - originX;
        const opposite = event.clientY - originY;
        const hypotenuse = Math.sqrt(adjacent ** 2 + opposite ** 2);

        let angle = Math.asin(opposite / hypotenuse);

        if(adjacent < 0) {
            angle = -(angle + Math.PI);
        }

        visualize(rotate(angle, []));
    };

//module ...