var stream = wkhtmltopdf(fs.createReadStream('file.html'));
but i need to navigate inside the directory where the file.html resides (/i.e: /data/files)so the relative paths inside the html file (./style.css ,... so on) is resolvable.
Note that it works with the following snippet:
execSync('wkhtmltopdf file.html file.pdf', {cwd: '/data/files'})