how to pretty print source code of common languages in browser html output with javascript?

Probably SyntaxHighlighter is the most popular. But you have a choice, have a look at 16 Free Javascript Code Syntax Highlighters For Better Programming

If you mean real time syntax highlighter, you can also try JS-CodeEdit:

JS-CodeEdit is a JavaScript editor that converts your HTML textareas into a code editor with realtime syntax highlighting. If added into a form, the content can be submitted e.g. to be written to a file. A nice thing is that you can add as many editors as you want within a HTML page.

But it support a bit limited list of languages: JavaScript, PHP, Perl, HTML, CSS, XML, SQL (this list is increased with each release).