Why does this JavaScript code fail to add style to text?
<pre><code>var css = ["font-family"];

var a = document.getElementById("t");

for (var i = 0; i &lt; a.length; i++) {
    a.style[css] = ["Arial"];
}

&lt;div id="t"&gt;Hello World&lt;/div&gt;
</code></pre>

<p>It doesn't add any font to it.</p>
