initial implementation of _.range

test/collections.js

@@ -2,6 +2,10 @@ $(document).ready(function() {
 
   module("Collection functions (each, any, select, and so on...)");
 
+  test("generators: range", function() {
+    equals(_.range(4).join(' '), '0 1 2 3 4', 'range with positive number generates an array of of elements 0,1,2,...,n');
+  });
+
   test("collections: each", function() {
     _.each([1, 2, 3], function(num, i) {
       equals(num, i + 1, 'each iterators provide value and iteration count');

underscore.js

@@ -33,6 +33,20 @@
   // Current version.
   _.VERSION = '0.4.5';
 
+  /*------------------------ Generator Functions: ----------------------------*/
+  _.range = function(upper, lower, step) {
+    if (!lower) var lower = 0;
+    if (!step) var step = 1;
+
+    var result = new Array(((upper - lower) / step) + 1));
+
+    for (var i = lower; i <= upper; i += step) {
+        result[i] = i;
+    }
+
+    return result;
+  }
+
   /*------------------------ Collection Functions: ---------------------------*/
 
   // The cornerstone, an each implementation.