CODEWITHSUNDEEP
javascript
Alwaysblue
Alwaysblue

Reputation: 11830

dot operaton in multiple functions calling

I was playing with Javascript and there is this one with thing which is puzzling me..

Suppose we have two functions 

function A (argA) {
 //Do Something with argA
 return somehingFromA
}

function B (argB) {
  //Do somwthing with argB
  return somethingFromB
}

if we want to pass return of A to B, we would probably do this B(A(arg))

this should give return of function A to B to process?

Now, when we do something like this 

arr.split(' ').join('-')

we are also pasing the return from split to join?

I know they both aren't equal, can someone tell me what I am thinking wrong?

Upvotes: 0

Views: 837

Answers (3)

DS Passionate
DS Passionate

Reputation: 86

For. Split(), It returns array. For join syntax is "array you want to join". Join(separator).

As array extend function join you are using this way.

Some functions need parameter but some datatype extend function to apply some operations.

I hope that clears your doubt

Upvotes: 1

T.J. Crowder
T.J. Crowder

Reputation: 1074258

I do see why you're confused, it is slightly subtle.

When you do B(A(arg)), you're passing A's return value into B. B sees that value as its parameter argB.

When you do arr.split(' ').join('-') you're using split's return value (an array) by calling a method on it, instead of passing the return value into join as an argument. join doesn't see the array as a parameter at all. (It does see it as this, because in the normal case when you do obj.method(), this within the call to method has the same value obj had. Which is what makes this slightly subtle.)

Upvotes: 2

cuddlemeister
cuddlemeister

Reputation: 1785

Methods are being applied to some objects. In your example .split() returns an array. join() is applied to that new array.

Upvotes: 0

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