I am tinkering with touchevents in js. I have encountered this error in my logcat in eclipse.

document.getElementById("squareBracket").
    addEventListener("touchmove", touchHandler, false);
document.getElementById("squareBracket").
    addEventListener("touchend", touchHandler, false);

function touchHandler(e) {
 if (e.type == "touchstart") {
 alert("You touched the screen!");
  } else if (e.type == "touchmove") {
 // alert(e.changedTouches[0].pageX);
 // alert(e.changedTouches[0].pageY);
 } else if (e.type == "touchend" || e.type == "touchcancel") {
  alert('X :' + e.targetTouches[0].pageX); 
  alert('Y :' + e.targetTouches[0].pageY);
}
}

If I remove the ment in the if in touchmove, the coordinates popup. However, if it is mented, the error in my logcat appears.

I am tinkering with touchevents in js. I have encountered this error in my logcat in eclipse.

document.getElementById("squareBracket").
    addEventListener("touchmove", touchHandler, false);
document.getElementById("squareBracket").
    addEventListener("touchend", touchHandler, false);

function touchHandler(e) {
 if (e.type == "touchstart") {
 alert("You touched the screen!");
  } else if (e.type == "touchmove") {
 // alert(e.changedTouches[0].pageX);
 // alert(e.changedTouches[0].pageY);
 } else if (e.type == "touchend" || e.type == "touchcancel") {
  alert('X :' + e.targetTouches[0].pageX); 
  alert('Y :' + e.targetTouches[0].pageY);
}
}

If I remove the ment in the if in touchmove, the coordinates popup. However, if it is mented, the error in my logcat appears.

• javascript
• android
• jquery
• cordova
• touchstart

Share Improve this question Follow edited May 13, 2014 at 8:11 Bhushan Kawadkar 28.5k55 gold badges3939 silver badges6060 bronze badges asked May 13, 2014 at 8:01 JeongbebsJeongbebs 4,12077 gold badges3535 silver badges6262 bronze badges 2

• First of all, the ments don't influence your logcat error. it seems e.targetTouches[0] is null or undefined. be aware it's changedTouches in first case and targetTouches in second case. – cosmincalistru Commented May 13, 2014 at 8:07
• so I should change it to changedtouches? – Jeongbebs Commented May 13, 2014 at 8:09

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 5

You should start understanding the difference of targetTouches, changedTouches and touches here: Variation of e.touches, e.targetTouches and e.changedTouches

in your case in the moment of touchend or touchcancel the targetTouches list is empty and the information remains in changedTouches.

changing your code to:

alert('X :' + e.changedTouches[0].pageX); 
alert('Y :' + e.changedTouches[0].pageY);

should do the trick.