The length read-only property indicates the number of items (touch points) in a given TouchList.
The number of touch points in touchList.
This code example illustrates the use of the TouchList interface's item method and the length property.
const target = document.getElementById("target");
target.addEventListener("touchstart", (ev) => {
// If this touchstart event started on element target,
// set touch to the first item in the targetTouches list;
// otherwise set touch to the first item in the touches list
const touch =
ev.targetTouches.length >= 1
? ev.targetTouches.item(0)
: ev.touches.item(0);
});