Generalize _.compact

index.html

@@ -200,6 +200,7 @@
       <li>- <a href="#reduceRight">reduceRight</a></li>
       <li>- <a href="#find">find</a></li>
       <li>- <a href="#filter">filter</a></li>
+      <li>- <a href="#compact">compact</a></li>
       <li>- <a href="#where">where</a></li>
       <li>- <a href="#findWhere">findWhere</a></li>
       <li>- <a href="#reject">reject</a></li>
@@ -226,7 +227,6 @@
       <li>- <a href="#initial">initial</a></li>
       <li>- <a href="#last">last</a></li>
       <li>- <a href="#rest">rest</a></li>
-      <li>- <a href="#compact">compact</a></li>
       <li>- <a href="#flatten">flatten</a></li>
       <li>- <a href="#without">without</a></li>
       <li>- <a href="#union">union</a></li>
@@ -499,6 +499,17 @@ <h2 id="collections">Collection Functions (Arrays or Objects)</h2>
 =&gt; [2, 4, 6]
 </pre>
 
+      <p id="compact">
+        <b class="header">compact</b><code>_.compact(list)</code>
+        <br />
+        Returns a copy of the <b>list</b> with all falsy values removed.
+        In JavaScript, <i>false</i>, <i>null</i>, <i>0</i>, <i>""</i>,
+        <i>undefined</i> and <i>NaN</i> are all falsy.
+      </p>
+      <pre>
+_.compact([0, 1, false, 2, '', 3]);
+=&gt; [1, 2, 3]
+</pre>
       <p id="where">
         <b class="header">where</b><code>_.where(list, properties)</code>
         <br />
@@ -753,18 +764,6 @@ <h2 id="arrays">Array Functions</h2>
       <pre>
 _.rest([5, 4, 3, 2, 1]);
 =&gt; [4, 3, 2, 1]
-</pre>
-
-      <p id="compact">
-        <b class="header">compact</b><code>_.compact(array)</code>
-        <br />
-        Returns a copy of the <b>array</b> with all falsy values removed.
-        In JavaScript, <i>false</i>, <i>null</i>, <i>0</i>, <i>""</i>,
-        <i>undefined</i> and <i>NaN</i> are all falsy.
-      </p>
-      <pre>
-_.compact([0, 1, false, 2, '', 3]);
-=&gt; [1, 2, 3]
 </pre>
 
       <p id="flatten">

test/arrays.js

@@ -53,12 +53,6 @@ $(document).ready(function() {
     equal(_.last(null), undefined, 'handles nulls');
   });
 
-  test("compact", function() {
-    equal(_.compact([0, 1, false, 2, false, 3]).length, 3, 'can trim out all falsy values');
-    var result = (function(){ return _.compact(arguments).length; })(0, 1, false, 2, false, 3);
-    equal(result, 3, 'works on an arguments object');
-  });
-
   test("flatten", function() {
     var list = [1, [2], [3, [[[4]]]]];
     deepEqual(_.flatten(list), [1,2,3,4], 'can flatten nested arrays');

test/collections.js

@@ -155,6 +155,13 @@ $(document).ready(function() {
     strictEqual(_.find(array, function() { return false; }), void 0, 'should return `undefined` if `value` is not found');
   });
 
+  test("compact", function() {
+    equal(_.compact([0, 1, false, 2, false, 3]).length, 3, 'can trim out all falsy values from an array');
+    deepEqual(_.compact({a: 0, b: 1, c: 2, d: false, e: 3, f: NaN}), {b: 1, c: 2, e: 3}, 'can trim out all falsy values from an object');
+    var result = (function(){ return _.compact(arguments).length; })(0, 1, false, 2, false, 3);
+    equal(result, 3, 'works on an arguments object');
+  });
+
   test('detect', function() {
     var result = _.detect([1, 2, 3], function(num){ return num * 2 == 4; });
     equal(result, 2, 'found the first "2" and broke the loop');

underscore.js

@@ -176,6 +176,24 @@
     return results;
   };
 
+  // Trim out all falsy values from an array or object.
+  _.compact = function(obj) {
+    var keys = Object.keys(obj);
+    for (var i = 0; i < keys.length; i++) {
+      if (keys[i] != i) {
+        var copy = {};
+        each(obj, function(value, key) {
+          if(value)
+            copy[key] = obj[key];
+        });
+        return copy;
+      }
+    }
+    if (_.isObject(obj))
+      obj = slice.call(obj);
+    return _.filter(obj, _.identity);
+  };
+
   // Return all the elements for which a truth test fails.
   _.reject = function(obj, iterator, context) {
     return _.filter(obj, function(value, index, list) {
@@ -415,11 +433,6 @@
     return slice.call(array, (n == null) || guard ? 1 : n);
   };
 
-  // Trim out all falsy values from an array.
-  _.compact = function(array) {
-    return _.filter(array, _.identity);
-  };
-
   // Internal implementation of a recursive `flatten` function.
   var flatten = function(input, shallow, output) {
     each(input, function(value) {