Edit in JSFiddle

document.getElementById("genBlob").onclick = function() {
  var xhr = new XMLHttpRequest();
  xhr.open("GET", "//fiddle.jshell.net/img/logo.png", true);
  xhr.responseType = "arraybuffer";
  xhr.onload = function(e) {
    var arrayBufferView = new Uint8Array(this.response);
    var blob = new Blob([arrayBufferView]);
    var urlCreator = window.URL || window.webkitURL;
    var imageUrl = urlCreator.createObjectURL(blob);
    var url = document.createElement("a");
    url.href = imageUrl;
    url.innerHTML = "Blob link";
    url.download = "";
    document.getElementById("result").appendChild(url);
    //window.URL.revokeObjectURL(imageUrl);
  };
  xhr.send();
}

<button id="genBlob">Generate blob link</button>
<div id="result"></div>