download a image using javascript from the image url

gistfile1.js

var a = document.createElement('a');

var e = document.createEvent("MouseEvents");
e.initMouseEvent("click", !0, !0, window, 1, 0, 0, 0, 0, !1, !1, !1, !1, 0, null);
a.setAttribute("href", 'http://www.baidu.com/img/bdlogo.gif'); //the image url
a.setAttribute("download", "kkk.png"); // the file name
a.dispatchEvent(e);