What is the output ? Can anyone explain the process?

Question

<script>
function addition(a=1,b=2,c){
return a+b+c;
}
console.log(addition(3));
</script>

Answer 1

If no parameter is passed in place of a,b,c then the default params are
a=1
b=2
c=undefined

But in above function, the params passed are:
a=3
b=2
c= undefined
If no param is passed then the default value is either decided by user using '=' symbol.
If not decided then the default value is 'undefined'

And any number of is added to undefined returns 'NaN'.

Hence output is NaN.

Answer 2

The value passed '3' is stored in variable/parameter 'a'.

So, a=3

The value of 'b' which needs to be second argument, is not passed. So the default value is '2'

So, b=2

The value of 'c' which needs to be third argument, is not passed.
The default value of c is not set.
So by system default, the value by default becomes 'undefined'

So, c=undefined

And finally,
a+b+c
=3+2+undefined
=5+undefined
=NaN

So that function returns NaN.
console.log(addition (3))
=console.log(NaN)

So output is NaN.

Please do not hesitate to ask me if you have any confusion. "I am always to help"

Answer 3

Ohk thank for clear my confusion😊

Answer 4

And what is the meaning of console.log(addition (3));why it pass the value of 3 ?