diff --git a/templates/main.js b/templates/main.js
index b3219b3c..78e7cbf1 100644
--- a/templates/main.js
+++ b/templates/main.js
@@ -1,5 +1,27 @@
 {% raw %}
 
+/* gettext-compatible _ function, example of usage:
+ *
+ * > // Loading pl_PL.json here (containing polish translation strings generated by tools/locale_compile.php)
+ * > alert(_("Hello!"));
+ * Witaj!
+ */
+function _(s) {
+	return (typeof tb_l10n != 'undefined' && typeof tb_l10n[s] != 'undefined') ? tb_l10n[s] : s;
+}
+
+/* printf-like formatting function, example of usage:
+ *
+ * > alert(fmt("There are {0} birds on {1} trees", [3,4]));
+ * There are 3 birds on 4 trees
+ * > // Loading pl_PL.json here (containing polish translation strings generated by tools/locale_compile.php)
+ * > alert(fmt(_("{0} users"), [3]));
+ * 3 uzytkownikow
+ */
+function fmt(s,a) {
+	return s.replace(/\{([0-9]+)\}/g, function(x) { return a[x[1]]; });
+}
+
 var saved = {};