Incrementing a number with JavaScript returns an error
<pre><code>var count = {
    digit: 0,
    increment: function() {
        setInterval(function() {
            count.digit++;
        }, 500);
        if (count == 10) {
            count.increment = null;
        }
    }
};
document.write("The number is " + count.digit);
count.increment();
</code></pre>

<p>The result is: "The number is 0" but it does not increment. Why?</p>
