Increase the font size with a click of a button using only JavaScript
<p>I'm attempting to increase the font size with the click of a button. I have got the first one to work but I can't get my head around the second one. The second one, every click will increase the font by 1px (I'm pretty much stuck):</p>

<pre><code>&lt;input type="button" value="Increase Font Size 100px" onclick="increaseFontSizeBy100px()"&gt;
&lt;p id="a"&gt;Font Size&lt;/p&gt;

&lt;input type="button" value="Increase Font Size 1px" onclick="increaseFontSizeBy1px()"&gt;
&lt;p id="b"&gt;Font Size by 1 Pixel&lt;/p&gt;

&lt;script&gt; 
    function increaseFontSizeBy100px() {
        document.getElementById('a').style.fontSize = "100px";
    }

    function increaseFontSizeBy1px() {
        var font = document.getElementById('b').style.fontSize;            
        font++;
    }
&lt;/script&gt;
</code></pre>