Merge pull request mde#117 from beeftornado/fixWidth-perf

Improve speed of _fixWidth

Author: longlho

spec/date.spec.js

@@ -2,6 +2,16 @@ var TestUtils = require('./test-utils')
 , timezoneJS = TestUtils.getTimezoneJS();
 
 describe('timezoneJS.Date', function () {
+  it('should correctly trim dates when date exceeds format length', function () {
+    var date = new timezoneJS.Date(2011, 10, 22);
+    expect(date.toString('yy-MM-dd')).toEqual('11-11-22')
+  });
+
+  it('should correctly pad dates when date is shorter than the format length', function () {
+    var date = new timezoneJS.Date(2011, 3, 2);
+    expect(date.toString('yyyy-MM-dd')).toEqual('2011-04-02')
+  });
+
   it('should have correct format when initialized', function () {
     var date = new timezoneJS.Date();
     expect(date.toString()).toMatch(/[\d]{4}(-[\d]{2}){2} ([\d]{2}:){2}[\d]{2}/);

src/date.js

@@ -114,19 +114,25 @@
   //
   // `_fixWidth(2, 2) = '02'`
   //
-  // `_fixWidth(1998, 2) = '98'`
+  // `_fixWidth(1998, 2) = '98'`  // year, shorten it to the 2 digit representation
+  // 
+  // `_fixWidth(23, 1) = '23'`  // hour, even with 1 digit specified, do not trim
   //
   // This is used to pad numbers in converting date to string in ISO standard.
   var _fixWidth = function (number, digits) {
     if (typeof number !== "number") { throw "not a number: " + number; }
+    var trim = (number > 1000);   // only trim 'year', as the others don't make sense why anyone would want that
     var s = number.toString();
-    if (number.length > digits) {
-      return number.substr(number.length - digits, number.length);
+    var s_len = s.length;
+    if (trim && s_len > digits) {
+      return s.substr(s_len - digits, s_len);
     }
-    while (s.length < digits) {
-      s = '0' + s;
+    s = [s];
+    while (s_len < digits) {
+      s.unshift('0');
+      s_len++;
     }
-    return s;
+    return s.join('');
   };
 
   // Abstraction layer for different transport layers, including fleegix/jQuery/Zepto