如何在加载到html之前获取图像大小？

var img = new Image();
img.src = 'your-image-url';
img.onload = function() {
  var width = this.width;
  var height = this.height;
  console.log('Image dimensions:', width, 'x', height);
};

<img src="your-image-url" width="your-width" height="your-height" />

img {
  width: your-width;
  height: your-height;
}