Question

I want to add either a scroll event listener or a touchstart event listener. Initially I used the touch event to deactivate the scroll event listener as shown in the code below:

window.addEventListener('scroll', scrollStart, false);
window.addEventListener('touchstart', touchStart, false);

function scrollMenu() {
    // do something
}

function touchStart(e) {
    window.removeEventListener('scroll', scrollStart);
    // do something
}

But I realized that on some occasions, the scroll event is triggered as soon as the page loads. Therefore, I cannot use the aforementioned method. Is there another way to check if the browser supports a touch event listener without adding the event?

Answer 1

You should be able to check whether the ontouchstart attribute exists in the window:

if ("ontouchstart" in window) {
    window.addEventListener('touchstart', touchStart, false);
} else {
    window.addEventListener('scroll', scrollStart, false);
}

… I can’t confirm the x-browser-ness of this though.