Make the unique token persistent, to avoid refreshes inflating the numbers.

[remoteglot] / www / js / remoteglot.js

diff --git a/www/js/remoteglot.js b/www/js/remoteglot.js
index 595bce185aa1a3457dc89cb5241fe5abee9c307e..c18349378cd2aac2c592246c9e7d764de5c86da7 100644 (file)
--- a/www/js/remoteglot.js
+++ b/www/js/remoteglot.js
@@ -48,8 +48,8 @@ var highlight_to = undefined;
 /** @type {?jQuery} @private */
 var highlighted_move = null;
 
-/** @type {!number} @private */
-var unique = Math.random();
+/** @type {?number} @private */
+var unique = null;
 
 /** The current position on the board, represented as a FEN string.
  * @type {?string}
@@ -76,6 +76,28 @@ var current_display_line = null;
 /** @type {?number} @private */
 var current_display_move = null;
 
+var supports_html5_storage = function() {
+       try {
+               return 'localStorage' in window && window['localStorage'] !== null;
+       } catch (e) {
+               return false;
+       }
+}
+
+// Make the unique token persistent so people refreshing the page won't count twice.
+// Of course, you can never fully protect against people deliberately wanting to spam.
+var get_unique = function() {
+       var use_local_storage = supports_html5_storage();
+       if (use_local_storage && localStorage['unique']) {
+               return localStorage['unique'];
+       }
+       var unique = Math.random();
+       if (use_local_storage) {
+               localStorage['unique'] = unique;
+       }
+       return unique;
+}
+
 var request_update = function() {
        $.ajax({
                url: "http://analysis.sesse.net/analysis.pl?ims=" + ims + "&unique=" + unique
@@ -809,6 +831,8 @@ var update_displayed_line = function() {
 }
 
 var init = function() {
+       unique = get_unique();
+
        // Create board.
        board = new window.ChessBoard('board', 'start');
        hiddenboard = new window.ChessBoard('hiddenboard', 'start');