while adding empty array and object, why console returns like this?

Question

I'm trying to print results for following combinations in chrome console. But could not able to understand results. why console returns following results. Can anyone please explain this?

[] + {} ==> "[object Object]"

{} + {} ==> "[object Object][object Object]"

{} + [] ==> 0

[] + [] ==> ""

score 2 · Accepted Answer · answered Mar 31 '18 at 16:42

2

If you add two objects (arrays are objects too), js will call toString for you, so

 [] + {}

is actually:

 [].toString() + {}.toString()

Stringifying an array joins its elements, and as the array is empty it will be stringified to "". Objects are always stringified to "[Object object]". That explains everything except:

 {} + []

... and thats a mistake on your side, it will return "[Object object]"

answered Mar 31 '18 at 16:42

Jonas Wilms

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@ Jonas. ... So what about this {} + [] ==> 0 ? – gopigoppu Apr 01 '18 at 06:56
@gopigoppu have a look at the duplicate ... it depends if you are in an expression context or not – Jonas Wilms Apr 01 '18 at 08:54

while adding empty array and object, why console returns like this?

1 Answers1