Well, I get the point that the title is clickbait-ish but I'm not sure what you mean you're not always able to use JavaScript? You can be in a position to choose your platform or not. If not, then you might also not be able to choose Go. If you can choose, you can also choose JavaScript. You don't necessarily need a webserver, you can write any sort of script and invoke it via node (though it's not as nice as being able to compile it and distribute it).