我已经创建了一个函数，可以从unsplash下载图像。但问题是，它对stackoverflow的代码段不起作用，因为它创建了 null BlobURL。您需要在服务器上运行此程序（如 localhost )，以便工作。
试穿一下-https://jsfiddle.net/xt5wb2vn/
html

<div id="container">
</div>
<button class="download">Click to download</button>

javascript

const numItemsToGenerate = 1;

function downloadImage(url) {
  let a = document.createElement("a");
  a.href = url;
  a.download = 'image.jpg';
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);

}

 function renderItem() {
   fetch(`https://source.unsplash.com/920x720?beach`)
  .then(resp => resp.blob())
  .then(image => {
    const image_url = URL.createObjectURL(image)
    let item = document.getElementById('container');
    item.innerHTML = `<img class="beach_image" src="${image_url}" alt="beach image"/>`;
    return image_url;
  }).then(url=>document.querySelector(".download").onclick = ()=>downloadImage(url))
}

renderItem()

使用 URL.createObjectURL 因此，函数应该如下所示

fetch(`https://source.unsplash.com/920x720?beach`)
  .then(resp => resp.blob())
  .then(image => {
    const image_url = URL.createObjectURL(image)
    const item = document.getElementById('container')
    item.src = image_url
  })