get the dataURL of specific url

gDataURL.js

  var gDataURL = function(opts){
    opts = opts || {};
    opts.onload = opts.onload || function(r){
      console.log(r);
    };
    opts.url = opts.url || location.href;

    var oReq = new XMLHttpRequest();
    oReq.open("GET", opts.url, true);
    oReq.responseType = "blob";
    oReq.setRequestHeader("Accept", "*/*");
    oReq.setRequestHeader("Accept-Encoding", "deflate");
    oReq.onload = function(oEvent) {
        var blob = oReq.response;
        var reader = new FileReader();
        reader.onload = function(oFREvent) {
            opts.onload(oFREvent.target.result);
        };
        reader.readAsDataURL(blob);
    };
    oReq.send();
  };
gDataURL({url: 'http://is.gy/', onload: function(r){alert(r)}});