how to set featured image in non-wordpress

I am wondering if I can dynamically set up a featured image through a Javascript tag. Is it possible to dynamically add a Google tag that runs only on certain pages and then run a script to put a meta tag with the value og:image inside the head and make the features image display on Facebook? Or do I somehow have to set it up manually in the backend somehow? I am thinking the web crawler may not detect it in time since it's added through javascript.