Default timezone

moment-timezone.js

@@ -342,8 +342,13 @@
 
 	moment.tz = tz;
 
+	moment.defaultZone = null;
+
 	moment.updateOffset = function (mom, keepTime) {
 		var offset;
+		if (mom._z === undefined) {
+			mom._z = moment.defaultZone;
+		}
 		if (mom._z) {
 			offset = mom._z.offset(mom);
 			if (Math.abs(offset) < 16) {
@@ -384,6 +389,11 @@
 	fn.zoneAbbr = abbrWrap(fn.zoneAbbr);
 	fn.utc      = resetZoneWrap(fn.utc);
 
+	moment.tz.setDefault = function(name) {
+		moment.defaultZone = name ? getZone(name) : null;
+		return moment;
+	};
+
 	// Cloning a moment should include the _z property.
 	var momentProperties = moment.momentProperties;
 	if (Object.prototype.toString.call(momentProperties) === '[object Array]') {

tests/moment-timezone/default.js

@@ -0,0 +1,76 @@
+"use strict";
+
+var moment = require("../../");
+
+exports.default = {
+	defaultZone : function (t) {
+		t.equal(
+			moment.defaultZone,
+			null,
+			'initial default zone should be null'
+		);
+		t.equal(
+			moment.tz.setDefault('America/New_York').defaultZone.name,
+			'America/New_York',
+			'calling moment.tz.setDefault with a valid timezone should expose it via defaultZone'
+		);
+		t.equal(
+			moment.tz.setDefault().defaultZone,
+			null,
+			'calling moment.tz.setDefault with a falsey argument should unset defaultZone'
+		);
+		t.done();
+	},
+	normal: function (t) {
+		moment.tz.setDefault('America/New_York');
+		var m = moment();
+		t.equal(
+			m._z.name,
+			'America/New_York',
+			'creating moments should set their default timezone if it is set'
+		);
+
+		moment.tz.setDefault();
+		var m2 = moment();
+		moment.tz.setDefault('America/New_York');
+		m2.millisecond(0);
+		t.equal(
+			m2._z,
+			null,
+			'calling updateOffset on moments created before setting a default timezone should not affect their timezone'
+		);
+		moment.tz.setDefault();
+		t.done();
+	},
+	utc : function (t) {
+		moment.tz.setDefault('America/New_York');
+		t.equal(
+			moment.utc().format('ZZ'),
+			'+0000',
+			'creating moments in UTC mode should ignore default timezone'
+		);
+		t.notEqual(
+			moment().format('ZZ'),
+			'+0000',
+			'using UTC mode should not affect normal moment creation'
+		);
+
+		var utc_moment = moment.utc(),
+		    normal_moment = moment(),
+		    normal_moment_offset = normal_moment.format('ZZ');
+		moment.tz.setDefault();
+		utc_moment.millisecond(0);
+		normal_moment.millisecond(0);
+		t.equal(
+			utc_moment.format('ZZ'),
+			'+0000',
+			'resetting default timezone should not affect existing moments created in UTC mode'
+		);
+		t.equal(
+			normal_moment.format('ZZ'),
+			normal_moment_offset,
+			'resetting default timezone should not affect existing moments'
+		);
+		t.done();
+	}
+};