JavaScript Essentials: The Engine

In this article, I want to explain what a software developer, who uses JavaScript to write applications, should know about engines so that the written code executes properly.
You see below a one-liner function that returns the property lastname of the passed argument. Just by adding a single property to each object, we end up with a performance drop of more than 700%!

Link: https://dzone.com/articles/javascript-essentials-thenbspengine