how to insert the data into xml using javascript?

Question

i have two text e.g.
<input id="txt1" type="text">
<input id="txt2" type="text">


now i want to insert these values into xml file using javascript.

xml file is :

<books>
<book>
<Author>abc</Author>
<Price> 300</Price>
<book>
<books>
thankyou...