modules/pointerEvents.js
function pointerDown(e) {
        // don't register an activePointer if more than one touch is active.
        var singleFinger = e.pointerType === POINTER_TYPE_MOUSE ||
            e.pointerType === POINTER_TYPE_PEN ||
            (e.pointerType === POINTER_TYPE_TOUCH && e.isPrimary);

        if (!isScrolling && singleFinger) {
            activePointer = {
                id: e.pointerId,
                clientX: e.clientX,
                clientY: e.clientY,
                x: (e.x || e.pageX),
                y: (e.y || e.pageY),
                type: e.pointerType
            };
        }
    }
function pointerDown(e) {
        // don't register an activePointer if more than one touch is active.
        var singleFinger = e.pointerType === POINTER_TYPE_MOUSE ||
            e.pointerType === POINTER_TYPE_PEN ||
            (e.pointerType === POINTER_TYPE_TOUCH && e.isPrimary);

        if (!isScrolling && singleFinger) {
            activePointer = {
                id: e.pointerId,
                clientX: e.clientX,
                clientY: e.clientY,
                x: (e.x || e.pageX),
                y: (e.y || e.pageY),
                type: e.pointerType
            };
        }
    }
function pointerDown ( e ) { // don't register an activePointer if more than one touch is active. var singleFinger = e . pointerType === POINTER_TYPE_MOUSE || e . pointerType === POINTER_TYPE_PEN || ( e . pointerType === POINTER_TYPE_TOUCH && e . isPrimary ) ; if ( ! isScrolling && singleFinger ) { activePointer = { id : e . pointerId , clientX : e . clientX , clientY : e . clientY , x : ( e . x || e . pageX ) , y : ( e . y || e . pageY ) , type : e . pointerType } ; } }
Handles the 'pointerdown' event from pointerEvents polyfill or native PointerEvents when supported.

@private
@param {MouseEvent|PointerEvent} e Event.
Handles the pointerdown event from pointerEvents polyfill or native PointerEvents when supported .