Merge branch 'feature/target-button'

* feature/target-button:
  Parse the file blob attributes rather than calling .data(); this ensures that we get the correct object in the event that the button is updated by new table data between downloads
  Unescape html when adding to an existing button
  Only set targets if they are defined

dist/js/tableexport.js

@@ -281,7 +281,9 @@
                         XLSX && key === 'xls' ? key = 'xlsm' : false;
                         !XLSX && key === 'xlsx' ? key = null : false;
                         var target;
-                        key in self.settings['targets'] ? target = self.settings['targets'][key] : null;
+                        if (self.settings['targets']) {
+                            key in self.settings['targets'] ? target = self.settings['targets'][key] : null;
+                        }
                         key && exporters[key](rowD, fileName, target);
                     }
                 );
@@ -298,6 +300,11 @@
                     }
                 }
 
+                function unescapeHtml(string) {
+                    var doc = new DOMParser().parseFromString(string, "text/html");
+                    return doc.documentElement.textContent;
+                }
+
                 function checkCaption(exportButton) {
                     var $caption = $el.find('caption:not(.head)');
                     $caption.length ? $caption.append(exportButton) : $el.prepend('<caption class="' + bootstrapSpacing + self.settings.position + '">' + exportButton + '</caption>');
@@ -310,14 +317,14 @@
 
                 function attachExportToButton(dataObject, target) {
                     var exportButton = $(target);
-                    exportButton.attr('data-fileblob', dataObject)
+                    exportButton.attr('data-fileblob', unescapeHtml(dataObject));
                 }
             });
 
             $("button[data-fileblob]")
                 .off("click")
                 .on("click", function () {
-                    var object = $(this).data("fileblob"),
+                    var object = JSON.parse($(this).attr('data-fileblob')),
                         data = object.data,
                         fileName = object.fileName,
                         mimeType = object.mimeType,