Calculating Age in Months and days
<pre><code>function getAge(dateString) {
    var today = new Date();
    var birthDate = new Date(dateString);
    var age = today.getFullYear() - birthDate.getFullYear();
    var m = today.getMonth() - birthDate.getMonth();
    if (m &lt; 0 || (m === 0 &amp;&amp; today.getDate() &lt; birthDate.getDate())) {
        age--;
    }
    document.write(age);

}

getAge("01/20/2011")
</code></pre>

<p>This shows me 0 years, but i would like to show <code>10 Months</code> and 9 Months until he his birthday comes <code>10/20/2011</code>. </p>
