using HTML5 a tag download attribute for download the Blob URL file All In One

using HTML5 a tag download attribute for download the Blob URL file All In One

Notice

download attribute only for HTML5 a or area tag ✅

download attribute not exist on HTML5 video tag ❌

When used on an anchor, this attribute signifies that the browser should download the resource the anchor points to rather than navigate to it.

https://caniuse.com/?search=download

https://html.spec.whatwg.org/multipage/links.html#downloading-resources

download Blob URL image

<section>
  <img id="img" />
  <a id="img-link" download>...loading</a>
</section>

// ES5
function generatorBlobURL(url, type, dom, link) {
  var xhr = new XMLHttpRequest();
  xhr.open('GET', url);
  xhr.responseType = 'arraybuffer';
  xhr.onload = function(res) {
    var blob = new Blob(
      [xhr.response],
      {'type' : type},
    );
    var urlBlob = URL.createObjectURL(blob);
    // render `blob` url ✅
    dom.src = urlBlob;
    // using `a` tag download ✅
    link.href = urlBlob;
    link.innerText = urlBlob;
    link.download = filename;
  };
  xhr.send();
}

(function() {
  var type = 'image/png';
  var url = 'https://cdn.xgqfrms.xyz/logo/icon.png';
  var dom = document.querySelector('#img');
  var link = document.querySelector('#img-link');
  var arr = url.split('/');
  var filename = arr[arr.length - 1] || 'default-filename';
  generatorBlobURL(url, type, dom, link, filename);
})();

download Blob URL video

<section>
  <video id="video" controls width="400" height="300">
    loading...
  </video>
  <br>
  <a id="video-link" download>...loading</a>
</section>

// ES5
function generatorBlobURL(url, type, dom, link) {
  var xhr = new XMLHttpRequest();
  xhr.open('GET', url);
  xhr.responseType = 'arraybuffer';
  xhr.onload = function(res) {
    var blob = new Blob(
      [xhr.response],
      {'type' : type},
    );
    var urlBlob = URL.createObjectURL(blob);
    // render `blob` url ✅
    dom.src = urlBlob;
    // using `a` tag download ✅
    link.href = urlBlob;
    link.innerText = urlBlob;
    link.download = filename;
  };
  xhr.send();
}

(function() {
  var type = 'video/mp4';
  var url = 'https://cdn.xgqfrms.xyz/HTML5/Blob/2022-04-07-sh.mp4';
  var dom = document.querySelector('#video');
  var link = document.querySelector('#video-link');
  var arr = url.split('/');
  // arr.at(-1);
  var filename = arr[arr.length - 1] || 'default-filename';
  setTimeout(() => {
    generatorBlobURL(url, type, dom, link, filename);
  }, 0);
})();

live demo

WebAssembly 防盗链：

1. 使用 WebAssembly 提供真实的连接 URL，然后使用 Blob URL 展示图片/ 视频等资源；
2. 由于 Blob URL 具有一定实效性，过一段时间就自动失效了，无法再次访问，这样就可以避免一些爬虫直接爬取到网站上资源的原始链接，从而一定程度上，避免山寨的爬虫网站直接盗用原始的资源和流量 ；

screenshots

API

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#attributes
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/area#attributes
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/map
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/video
https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes

area tag

refs

https://stackoverflow.com/a/71895888/5934465

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