Resize Image in JS

resize.ts

function resizeBase64Img(base64Str: string, maxWidth = 500, maxHeight = 500) {
  return new Promise<string>((resolve) => {
    const img = new Image();
    img.src = base64Str;
    img.onload = () => {
      const canvas = document.createElement('canvas');
      const MAX_WIDTH = maxWidth;
      const MAX_HEIGHT = maxHeight;
      let {width, height} = img;

      if (width > height) {
        if (width > MAX_WIDTH) {
          height *= MAX_WIDTH / width;
          width = MAX_WIDTH;
        }
      } else if (height > MAX_HEIGHT) {
          width *= MAX_HEIGHT / height;
          height = MAX_HEIGHT;
        }
      canvas.width = width;
      canvas.height = height;
      const ctx = canvas.getContext('2d');
      ctx?.drawImage(img, 0, 0, width, height);
      resolve(canvas.toDataURL());
    };
  });
}