CODEWITHSUNDEEP
callbackhigher-order-functions
JeroenT
JeroenT

Reputation: 5

What is the correct implementation of a callback function?

See two functions below. They lead to the same output [4,6], but are different in set up. Is it correct that only the first function makes use of a callback function? Is the first function preferred(more elegant?) over the other one? And is it correct that 'map' is the higher-order function in the second example as it makes use of the callback function that is within its brackets? Thanks! 

function processArray(arr,callback){
return arr.map(callback)
}

processArray([2,3], function(number){return number*2})

AND

function processArray(arr){
return arr.map(function(element){
return otherFunction(element)})
}

function otherFunction(number){
return number*2}

processArray([2,3])

Upvotes: 0

Views: 90

Answers (1)

Caleth
Caleth

Reputation: 62636

Is it correct that only the first function makes use of a callback function?

No. arr.map takes a callback. You just don't see its definition here.

Is the first function preferred(more elegant?) over the other one?

Yes, but (probably) not for the reason you think. The anonymous function wrapping otherFunction is pointless. You can also write

function processArray(arr){
  return arr.map(otherFunction)
}

function otherFunction(number){
  return number*2
}

processArray([2,3])

And is it correct that 'map' is the higher-order function in the second example as it makes use of the callback function that is within its brackets?

In the first example, both processArray and map are higher-order functions. In the second, yes, only map is higher-order.

It's easy to inspect a function to see if it is a higher-order function: is one (or more) of its parameters invoked?

Upvotes: 1

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