Getting the height and width of an image in Angular using TypeScript

Question

I'm trying to get the width and height of an image using its src URL.
This code outputs "undefinedxundefined" to the console.
This is what I have now:

  getImageSize(image: string) {
let width;
let height;
let img = new Image();
img.src = image;
img.onload = function (event) {
  let targetImg = event.currentTarget as HTMLImageElement;
  width = targetImg.width;
  height = targetImg.height
}
return width + "x" + height;

}

I'm using Angular version 12.2.11.