Addition of an object and empty array

#1

in both the cases it is showing output [object Object]
but it should show 0 in the first case and [object Object] in the second case

#2

You are logging {}+[]
That is why you are getting [object Object]
Instead of console.log({} + []) see the output without console.log()
i.e. Open the browser console and type {} + [] (without console.log)

To explain the difference between the two different outputs (i.e. 0 and [object Object]), you need to read about LHS and RHS lookup.
Read this: https://dev.to/maeganwilson_/lhs-rhs-look-ups-12ma

#3

After reading the article, now understand that when you write:
console.log({} + [])
Here we perform a RHS lookup of {}, which is an empty object. So it is basically adding empty object and empty array.
While in case of:
{} + []
we are performing a LHS lookup of {}, which is just an empty block of code. So basically we are trying adding an empty code block and empty array.

#4

Fore reference, here are some cases where RHS lookup is performed:

  1. Anything right of = is RHS
  2. Anything in function argument is also RHS
  3. Anything after a mathematical operator is also RHS
#5

I know what are you saying that’s why i am asking the question why both the statement are giving same output. Instead of giving {} + [] = 0 it is giving [object Object]. And console.log is function of interpreter which gives output so {} + [] should give 0 value on ide also or webstorm rather it is showing
[object Object]. It shouldn’t matter the platform the main task is of interpreter.

#6

When you pass something as an argument, always the RHS lookup is followed. The RHS lookup of {} is an empty object.
But when you write {}+[] without passing to it as parameter to console.log, LHS lookup is considered. LHS lookup of {} is an empty block of code.

#7

The platform here matters because you can only see the output on online ide with console.log(), while on a web browser, or an interpreter the result of each statement is printed.

#8

So if you are saying LHS lookup is done by console.log then [] + {} should give zero but instead it is giving object Object

#9

I said passing any parameter to console.log will invoke RHS lookup, not LHS lookup.

#10

And for []+{}, for both cases LHS and RHS, the lookup for [] is an empty array. After that an mathematical operator + is there. When a mathematical operator is reached, then always the RHS lookup is done for further part of the expression. The rhs of {} is an empty object. So basically it is an array + object in both cases (with or without console.log)

#11

@rishu1450 Is your doubt solved now?