Take advantage of native speed when we can

See #1999

diff --git a/moment.js b/moment.js
index 182b3c74392b1d6d883b3da53064603c1e1532c5..9a9ea96b15caa51e00702d4be49a70d05f6e0c87 100644 (file)
--- a/moment.js
+++ b/moment.js
@@ -2152,7 +2152,12 @@
         toISOString : function () {
             var m = moment(this).utc();
             if (0 < m.year() && m.year() <= 9999) {
-                return formatMoment(m, 'YYYY-MM-DD[T]HH:mm:ss.SSS[Z]');
+                if ('function' === typeof Date.prototype.toISOString) {
+                    // native implementation is ~50x faster, use it when we can
+                    return this.toDate().toISOString();
+                } else {
+                    return formatMoment(m, 'YYYY-MM-DD[T]HH:mm:ss.SSS[Z]');
+                }
             } else {
                 return formatMoment(m, 'YYYYYY-MM-DD[T]HH:mm:ss.SSS[Z]');
             }