JSFiddle - React, Tailwind, and code Playground

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()