These bookmarklets let you see how a web page is coded without digging through the source, debug problems in web pages quickly, and experiment with CSS or JS without editing the actual page.
It is possible in Javascript (ECMAScript) to do classical single inheritance nested to any depth, without any caveats.
This article concisely explores the mechanism in depth, including flaws in other approaches, internal Javascript algorithms, proper OOP data encapsulation with default constructors, and an optimized inheritance declaration syntax with both Object and Function prototype convenience methods.
R. Abbott, J. Guo, and B. Parviz. The 2003 International Conference on Machine Learning;
Models, Technologies and Applications (MLMTA'03), las Vegas, CSREA Press, (23-26 June 2003)