First, [] + {} isn't an object, it's a string.

Second, {} + [] isn't a type conversion issue, it's a parsing issue. That {} isn't an object, it's a code block. Assign {} to a variable to ensure it's an object, then do var + [] and you get the same result as the first one.

When using an actual object in both of these, the type conversion makes sense: "+" acts on primitives like strings and numbers, so it has to convert them first. You're getting obj.toString() + array.toString() in either case.

I'll admit the parsing issue here is odd, but most of the time peoples' complaints about javascript type coercion is that they simply never bothered to learn how it works.