问鼠标悬停在JS时如何缩放图像？

EN

function imageZoom(imgID, resultID) {

  var img, lens, result, cx, cy;

  img = document.getElementById('myimage');
  result = document.getElementById(resultID);

  lens = document.createElement("DIV");
  lens.setAttribute("class", "img-zoom-lens");

  img.parentElement.insertBefore(lens, img);

  cx = result.offsetWidth / lens.offsetWidth;
  cy = result.offsetHeight / lens.offsetHeight;

  result.style.backgroundImage = "url('" + img.src + "')";
  result.style.backgroundSize = (img.width * cx) + "px " + (img.height * cy) +
    "px";

  lens.addEventListener("mousemove", moveLens);
  img.addEventListener("mousemove", moveLens);

  lens.addEventListener("touchmove", moveLens);
  img.addEventListener("touchmove", moveLens);

  function moveLens(e) {

    var pos, x, y;

    e.preventDefault();

    pos = getCursorPos(e);


    x = pos.x - (lens.offsetWidth / 2);
    y = pos.y - (lens.offsetHeight / 2);

    if (x > img.width - lens.offsetWidth) {
      x = img.width - lens.offsetWidth;
    }
    if (x < 0) {
      x = 0;
    }
    if (y > img.height - lens.offsetHeight) {
      y = img.height -
        lens.offsetHeight;
    }
    if (y < 0) {
      y = 0;
    }

    lens.style.left = x + "px";
    lens.style.top = y + "px";

    result.style.backgroundPosition = "-" + (x * cx) + "px -" + (y * cy) + "px";
  }

  function getCursorPos(e) {
    var a, x = 0,
      y = 0;
    e = e || window.event;

    a = img.getBoundingClientRect();

    x = e.pageX - a.left;
    y = e.pageY - a.top;

    x = x - window.pageXOffset;
    y = y - window.pageYOffset;
    return {
      x: x,
      y: y
    };
  }
}

<div class="img-zoom-container" onmouseover="IsOver(true)" onmouseout="IsOver(false)">
  <img id="myimage" src="file:///C:/Users/balda/Desktop/prova%20JS/immagine1.png" onmousemove="imageZoom" width="300" height="300">
</div>