I'm sure any browser produced after year 2000 is able to process
JavaScript lol. In case you're confused, JavaScript is a scripting
language for the web. By disabling it, it means setting your
browser to ignore any JavaScript code in a web page.
Since it's BlogSpot, there's only 2 possibilities:
1. If I'm not wrong, BlogSpot has an option to allow bloggers to
make his/her blog private to a small group of people. You can't
bypass that.
2. He is using a JavaScript prompt() like what Pillow has
mentioned. Disable JS and you should be able to view his
blog.
A JS prompt() looks something like when you type in this in the
address/URL field of your browser:
javascript:prompt('wAts tEh pAsswrd?');