Which takes less memory: a Javascript array or Javascript object?
<p>If I have a Javascript list which will have only numeric keys, which takes less memory?</p>

<pre><code>var array = [];
array[0] = 'hello';
array[5] = 'world';
array[50] = 'foobar';

var obj = {};
obj[0] = 'hello';
obj[5] = 'world';
obj[50] = 'foobar';
</code></pre>

<p>I don't know a ton about Javascript engine internals, so...</p>

<p>The reason I ask is because that array, when converted to a string, will have a bunch of undefined's in the middle of it. Are those actually stored in some fashion, or is that just put in at string conversion?</p>
