canvas draw touch is not drawing

if I enter a position on lineTo() and moveTo() i have a line but if i give the touchstart and touchmove position nothing happens and i have bot console erreur to help me

touchStart(e){
  this.touchDessiner(e.changedTouches[0].pageX, e.changedTouches[0].pageY)
  console.log(e.changedTouches[0].pageX, e.changedTouches[0].pageY);
}
touchMove(e){
  e.preventDefault();
  this.touchDessiner(e.changedTouches[0].pageX, e.changedTouches[0].pageY)
  console.log(e.changedTouches[0].pageX, e.changedTouches[0].pageY)
}

  touchDessiner(x, y){
    this.cont.lineWidth = 2;
    this.cont.strokeStyle = "#000";
    this.cont.beginPath();
    this.cont.moveTo(x, y);
    this.cont.lineTo(x, y);
    this.cont.stroke();
  }

thanks for your help

Solution

Here is the correct order to draw lines:

On TouchStart:
1. start a new path (lift the pen from the canvas)
2. move the pen here

On TouchMove:
3. with the pen still touching the canvas, move the pen here

canvas = document.getElementById("can");
cont = canvas.getContext("2d");

function touchStart(e){
  this.cont.beginPath();
  this.cont.moveTo(e.changedTouches[0].pageX, e.changedTouches[0].pageY);
}

function touchMove(e){
  e.preventDefault();
  this.touchDessiner(e.changedTouches[0].pageX, e.changedTouches[0].pageY)
}

function touchDessiner(x, y){
  this.cont.lineWidth = 2;
  this.cont.strokeStyle = "#000";
  this.cont.lineTo(x, y);
  this.cont.stroke();
}

window.addEventListener("touchstart", touchStart);
window.addEventListener("touchmove", touchMove);

<!DOCTYPE html>
<html>
<body>
  
  canvas
  <canvas id = "can" style = "border: 1px solid black; position:absolute; left:0px; top:0px;"> </canvas>

</body>
</html>