Add "week" / "w" support

Closes #31.

index.js

@@ -6,6 +6,7 @@ var s = 1000;
 var m = s * 60;
 var h = m * 60;
 var d = h * 24;
+var w = d * 7;
 var y = d * 365.25;
 
 /**
@@ -49,7 +50,7 @@ function parse(str) {
   if (str.length > 100) {
     return;
   }
-  var match = /^((?:\d+)?\.?\d+) *(milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|years?|yrs?|y)?$/i.exec(
+  var match = /^((?:\d+)?\.?\d+) *(milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|weeks?|w|years?|yrs?|y)?$/i.exec(
     str
   );
   if (!match) {
@@ -64,6 +65,10 @@ function parse(str) {
     case 'yr':
     case 'y':
       return n * y;
+    case 'weeks':
+    case 'week':
+    case 'w':
+      return n * w;
     case 'days':
     case 'day':
     case 'd':
@@ -130,11 +135,13 @@ function fmtShort(ms) {
  */
 
 function fmtLong(ms) {
-  return plural(ms, d, 'day') ||
+  return (
+    plural(ms, d, 'day') ||
     plural(ms, h, 'hour') ||
     plural(ms, m, 'minute') ||
     plural(ms, s, 'second') ||
-    ms + ' ms';
+    ms + ' ms'
+  );
 }
 
 /**

tests.js

@@ -33,6 +33,10 @@ describe('ms(string)', function() {
     expect(ms('2d')).to.be(172800000);
   });
 
+  it('should convert w to ms', function() {
+    expect(ms('3w')).to.be(1814400000);
+  });
+
   it('should convert s to ms', function() {
     expect(ms('1s')).to.be(1000);
   });