Adding empty object and array

Question

I apologize in advance because this is somehow a silly question, but I just need to know WHY this happens and I didn't find the answer. So, there you go, stack overflow!

In this video (which I can't recommend enough) around 2:00 mark the guys shows that in Javascript:

[] + [] = empty string
[] + {} = object
{} + [] = 0
{} + {} = NaN

Anyone knows why?

JS has ALL SORTS OF implicit conversions based on the operator. JavaScript guru coming to explain each in 5...4...3.. — Adam Rackis
– Adam Rackis, Commented Jan 27, 2012 at 19:58
[] + {} is the string representation of an object, which is usually something like "[object Object]" jsconsole.com/?typeof%20(%5B%5D%20%2B%20%7B%7D) — dtanders
– dtanders, Commented Jan 27, 2012 at 20:13

seth.miller · Accepted Answer · 2012-01-27 20:11:41Z

6

This blog post by Adam Iley covers the reasoning behind most of those edge cases.

(Note: The site is having some database problems. You can use the google cache until they fix things.)

answered Jan 27, 2012 at 20:11

seth.miller

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