为什么我会显示外部URL,但由于CORS而无法获取它?

如果这是一个基本问题,请原谅我。

I am scrapping a certain website and i get links of images from that website. When i present those images in an album using js, using urls from the external website - i can see all the photos without a problem. (using img tag)

Later, i would like to fetch the images, in order to save them (as blobs) to a server. I use fetch :

  fetch('https://.........jpg')
  .then(res => res.blob())
  .then(blob => {
       console.log(blob);
    });

这将在浏览器中显示CORS错误。 (但不在模拟器中本地!)

headers of the link (looking at Chrome network) don't have Access-Control-Allow-Origin header.

  1. 为什么我可以显示它们但不能获取它们?两种情况都获得照片的二进制数据(?)
  2. 无论如何,我将如何获取图像数据?