Javascript ++ vs +=1
<pre><code>var a = "ab";
var b = "ab";
a+=1; // "ab1"
b++; // "NaN"
</code></pre>

<p>(Tested on chrome's V8)</p>

<p>Can someone explain why the results are different based on the internal atomic actions of the <code>++</code> arithmetic operator and the <code>+=</code> assignment operator with argument <code>1</code></p>
