apache map file path to different sub url

Suppose I have the following set up:

/www/member/ -> contains the site for members, map to localhost/member
/www/admin/  -> contains the site for admin, map to localhost/admin

How should I configure apache so that

when files in /www/member requests for /main.js, the server returns localhost/member/main.js (located in /www/member/main.js).

In other words, the / directory in the member site becomes /www/member?

The same is true for admin.