If you have problems like that, you can always read on documentation. also
console.log(typeof Kinetic.document.createWindow);
Also if u do not have access to source code or u can not simply find it. u can always output javascript code via simply reading it with simple I/O
http://serebrov.github.io/html/2013-12-02-node-core-module-source.html
here is example
fs = require('fs');
fs.writeFileSync('fs.js', fs.toString());
fs.writeFileSync('fs.readFileSync.js', fs.readFileSync.toString());
this will copy the source code of fs to new js file that u can read.