Add max_units option to stringify, so that the maximum unit is specified

juration.js

@@ -92,14 +92,22 @@
       throw "juration.stringify(): format cannot be '" + options.format + "', and must be either 'micro', 'short', or 'long'";
     }
 
+    if((typeof options === 'object' && options.max_units !== undefined) && (options.max_units !== 'years' && options.max_units !== 'months' && options.max_units !== 'days' && options.max_units !== 'hours' && options.max_units !== 'minutes' && options.max_units !== 'seconds')) {
+      throw "juration.stringify(): max_units cannot be '" + options.max_units + "', and must be either 'years', 'months', 'days', 'hours', 'minutes', or 'seconds'";
+    }
+
     var defaults = {
-      format: 'short'
+      format: 'short',
+      max_units: 'years'
     };
 
     var opts = _extend(defaults, options);
 
     var units = ['years', 'months', 'days', 'hours', 'minutes', 'seconds'], values = [];
+    var index = units.indexOf(opts.max_units);
+    units = units.slice(index);
     var remaining = seconds;
+
     for(var i = 0, len = units.length; i < len; i++) {
       var unit = UNITS[units[i]];
       values[i] = Math.floor(remaining / unit.value);

test/index.html

@@ -169,6 +169,11 @@
     raises(function(){juration.stringify(8400, { format: 'horses' });});
   });
 
+  test("stringify and specify largest unit", function() {
+    var parsed = juration.stringify(129600, { max_units: 'hours' });
+    equal(parsed, "36 hrs", "We expect 129600 to be 36 hrs");
+  });
+
 });
 
 </script>