Distinguish between left and right mouse clicks

ele.addEventListener('mousedown', function (e) {
    // e.button === 0: the left button is clicked
    // e.button === 1: the middle button is clicked
    // e.button === 2: the right button is clicked
    // e.button === 3: the `Browser Back` button is clicked
    // e.button === 4: the `Browser Forward` button is clicked
});