输出 ImageData 对象的高度 - 在线编辑器

          <canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
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</canvas>
<script>
  var c = document.getElementById("myCanvas");
  var ctx = c.getContext("2d");
  var imgData = ctx.createImageData(100, 100);
  alert("Height of imgData is: " + imgData.height);
  for (var i = 0; i < imgData.data.length; i += 4) {
    imgData.data[i + 0] = 255;
    imgData.data[i + 1] = 0;
    imgData.data[i + 2] = 0;
    imgData.data[i + 3] = 255;
  }
  ctx.putImageData(imgData, 10, 10);
</script>
        