Create preventUnload.js

preventUnload.js

@@ -0,0 +1,18 @@
+/** Do not reload a page nor navigate away while blacklisting in bulk.
+ *
+ * When `form.bulk_images` exist (that is, applies for bulk blacklisting only) and
+ * as soon as `selectedImages` get passed to the request data,
+ * allow for leaving the page.
+ *
+ * Docs:
+ *     https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onbeforeunload
+ */
+var preventUnload = function (e) {
+   'use strict';
+   $(window).on('beforeunload', function(e) {
+        var message = "Blacklisting process in progress.";
+        // e.returnValue = message;
+        console.log(message);
+        return message;
+   })
+};