Show number of finger touch screen in Real time

show_finger_real_time.js

$("#camera-controller").on("touchstart", (e) => {
    var fingerOnScreen = e.originalEvent.targetTouches.length;
    $('#finger_count').text(fingerOnScreen);
});
$("#camera-controller").on("touchend", (e) => {
    var fingerOnScreen = e.originalEvent.targetTouches.length;
    $('#finger_count').text(fingerOnScreen);
});

Here is simple sample code, hope it help

Longer version

$("#camera-controller").on("touchstart", (e) => {
    e.preventDefault();
    var fingerOnScreen = e.originalEvent.targetTouches.length;
    // $('#finger_count').text(fingerOnScreen);
    place.touchingFinger = fingerOnScreen; // save it to somewhere else so we can use it later
});

var originalDistance = null;
$("#camera-controller").on("touchmove", (e) => {
    e.preventDefault();
    if(place.touchingFinger == 2){
        var x1 = e.originalEvent.changedTouches[0].clientX
        var y1 = e.originalEvent.changedTouches[0].clientY

        var x2 = e.originalEvent.changedTouches[1].clientX
        var y2 = e.originalEvent.changedTouches[1].clientY

        var a = x1 - x2;
        var b = y1 - y2;
        var c = Math.sqrt( a*a + b*b );

        if(originalDistance == null){
            originalDistance = c;
        }
        var change = c - originalDistance
        var newScale = place.zooming.zoomScale + (change/100);
        $('#finger_count').text(change);
        place.setZoomScale(newScale);
    }
});

$("#camera-controller").on("touchend", (e) => {
    e.preventDefault();
    var fingerOnScreen = e.originalEvent.targetTouches.length;
    // $('#finger_count').text(fingerOnScreen);
    place.touchingFinger = fingerOnScreen;
    if(fingerOnScreen <= 1){
        originalDistance = null;
    }
});