Have you included all jsPDF lib files?
<script type="text/javascript" src="jspdf.js"></script>
<script type="text/javascript" src="./libs/FileSaver.js/FileSaver.js"></script>
<script type="text/javascript" src="./libs/Blob.js/Blob.js"></script>
<script type="text/javascript" src="./libs/Blob.js/BlobBuilder.js"></script>
<script type="text/javascript" src="./libs/Deflate/deflate.js"></script>
<script type="text/javascript" src="./libs/Deflate/adler32cs.js"></script>