How to pluck the second value in a url after the first slash, in a string that could have many slashes?

I know there are countless regex questions out there, but I was unable to find one that fits my situation.

Suppose I have the following pathname:

/u/some_user/create/initial

How can I extract 'some_user' from this string?

I got pretty close with this:

const pathname = '/u/some_user/create/initial';

const result = pathname.match(/(\/u\/)(.{1,}\/)(.+)/);

console.log('result', result);

This could potentially work if the string was '/u/some_user/create' -- It would return some_user/, and I could filter out the slash at the end. But if the string has more slashes, as above, then this just returns 'some_user/create/'.

How can I achieve plucking out just 'some_user'?