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

• 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

1 Answer 1

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.