First of all, thanks for kind words. I'm glad you found this post useful. I think I should have given more attention to use cases of `delete` before delving in

First of all, thanks for kind words. I'm glad you found this post useful. I think I should have given more attention to use cases of `delete` before delving into all the details of how it works :) My bad. I wouldn't say using `delete` is almost always the wrong approach, but it is certainly often misunderstood. There are valid use cases where one needs to delete a property, usually before iterating over an object (and performing some operation on each of the remaining properties), or when using `in` operator to detect property existence. Note that simply assigning `undefined` doesn't delete property — it is still visible during iteration or when inspecting object with `in`/`Object#hasOwnProperty`. In practice, I immediately think of event abstraction, where `delete` is often useful. In fact, jQuery uses it just for this kind of purpose — http://github.com/jquery/jquery/blob/master/src/event.js#L158 http://github.com/jquery/jquery/blob/master/src/event.js#L15.... In Prototype.js, there are also a couple of places where we use `delete` (such as to delete a property from an object for some special purpose (take care of IE bug) and then iterate over the remaining properties of an object — http://github.com/sstephenson/prototype/blob/master/src/dom/dom.js#L134 http://github.com/sstephenson/prototype/blob/master/src/dom/...) The idea was to explain what can and can not be deleted; that deleting variables is useless (and even not future-compatible), unless those are declared from within eval (very unlikely); that deleting host objects is dangerous. Everything else — i.e. deleting user-defined object properties — can and should be done in the right context ;)