As the error suggest you need to supply a source document or an initial template.
Something like:
<script>
var onSaxonLoad = function() {
Saxon.run( {
stylesheet: "books.xsl",
source: "books.xml"
});
or
<script type="text/javascript"> var onSaxonLoad = function() { proc = Saxon.run( {
stylesheet: 'scripts/stylesheet.xsl', initialTemplate: 'main' } ); };
</script>
Take a look at:
http://www.saxonica.com/ce/user-doc/1.1/index.html#!starting/running