Almost all of those methods use approximately the same amount of memory, though the performance varies drastically.

The key is that few people know what's actually going on underneath the JavaScript interpreter engine. In some cases it could be doing something really clever, and in other cases it could be doing something really stupid. Only ways to find out is to read the source, or benchmark. :P

my point exactly.

grid data structures in JS as already beaten to death. there's only the canvas that can be arguably be called new in that article.

But the final fact about JS performance is to understand/benchmark how every browser type/version will do something under the hood.