static javascript files are downloaded from server to client browser and runs there right?

if I have a .js file with contents below,

fetch("/api/users")

I believe this resolves to full URL of its server's domain or IP address. (such as https://my.server.com/api/users)

But how does this script knows that itself came from host my.server.com and therefore should prefix with that host name?

I mean, scripts are just independent files and does not know about environment it is running at.

CodePudding user response：

But how does this script knows that itself came from host my.server.com and therefore should prefix with that host name?

It's part of the specification of the fetch API, specifically:

3. Let baseURL be this’s relevant settings object’s API base URL.

Which itself links off to various other places defining 3 different things specifying those.

In short, it's not anything the scripts themselves that are running are doing - it's the implementation of fetch that's doing it, whether that's provided by the browser, or a serverside runtime such as Node etc.