Can't get serveStatic to work with `root`

I'm a bit confused here:

app.use("/static/*", serverStatic({ root: "./static"}))

app.use("/static/*", serverStatic({ root: "./static"}))

can't resolve

/static/myscript.js

/static/myscript.js

But

app.use("/myscript", serveStatic({ path: "./static/assets/myscript.js"})

app.use("/myscript", serveStatic({ path: "./static/assets/myscript.js"})

does work when accessing

/myscript

/myscript

Folder structure is:
- src
- static
- assets
- myscript.js