Long and short of the story is, whilst reading John Resig's blog (specifically http://ejohn.org/blog/javascript-trie-performance-analysis/) I came across a line which makes absolutely no sense to me whatsoever. Essentially it boils down to object = object[key] = something; (this can be found in the first code block of the article I've linked.) This has proven rather difficult to google, so if anyone can offer some insight / a good online resource for me to learn for myself, I'd much appreciate it.