You can use a basic cookie script to keep visitors (that don't have the cookie on their system) from viewing certain parts of your site (kind of.... There are always ways around it). The cookie is placed when the password provided is correct. Then,
Developer: javascript.internet.com Platform: Independent Date upd:1999-08-22 Hits10070 [Visit]

This user friendly script allows you to password protect your Web site/pages. The password is the filename without the .html ending. This password for this example is gatekeeper-in.
Developer: javascript.internet.com Platform: Independent Date upd:1999-08-22 Hits7980 [Visit]

Have you ever wanted to password protect a web page but did not know how? Well your problems are solved with Key Keeper. This is one of the first password protection JavaScripts that will allow multiple users (multiple passwords).
Developer: members.aol.com Platform: Independent Date upd:1999-12-18 Hits13947 [Download] [Visit]

If you want to 'protect' a site and don't have CGI access, you can try this JavaScript. Visitors get three tries to enter the correct password then they are refused entry. The password of this example is: password.
Developer: javascript.internet.com Platform: Independent Date upd:1999-08-22 Hits3933 [Visit]

Use this script to block certain IPs from your webpage, by redirecting them to another site. Uses SSI to determine the user's IP, and JavaScript to block access.
Developer: JavaScript Kit Platform: linux, windows Date upd:2005-06-22 Hits2960 [Visit]