In javascript, when would a === comparison of two 'equal' strings return false?
<p>Each of the following two items contain the same string value but the comparison using '===' returns false.</p>

<pre><code>(hiddenColumns[hidenColsIndex] === cells[metricColsIndex].columnName)
</code></pre>

<p>This comparison using '==' returns true</p>

<pre><code>(hiddenColumns[hidenColsIndex] == cells[metricColsIndex].columnName)
</code></pre>

<p>Why?</p>
