canvas手写签名

<script>
  let canvas = document.createElement("canvas");
  canvas.width = window.innerWidth;
  canvas.height = window.innerHeight;
  document.body.appendChild(canvas);
  let context = canvas.getContext("2d");
  canvas.addEventListener("mousedown", function (e) {
    this.isMouseDown = true;
    context.moveTo(e.pageX, e.pageY);
  });
  canvas.addEventListener("mousemove", function (e) {
    if (this.isMouseDown) {
      context.lineTo(e.pageX, e.pageY);
      context.stroke();
    }
  });
  canvas.addEventListener("mouseup", function (e) {
    this.isMouseDown = false;
  });
</script>