How to return a variable from a callback?

Question

I'm a newbie and now I'm having trouble returning a value from a callback function

function SumCallback(var1,var2,callback){
callback(var1+var2)
}

function Sum(var1,var2){
SumCallback(var1,var2,function(result){
console.log(result) //5
return result
})
}

console.log(Sum(3,2)) //undefined

How can I return the value in the correct way?

Answer 1

The execution looks like that

|-> This calls "SumCallback"

|--> This calls the "callback"

|---> This calls console.log(result)

|---> return "result"

|--> return undefined

|-> return undefined

You only need to return the callback.

function SumCallback(var1,var2,callback){
 return callback(var1+var2)
}

function Sum(var1,var2){
 return SumCallback(var1,var2,function(result){
  console.log(result) //5
  return result
 })
}

console.log(Sum(3,2)) //5

The new execution looks like that

|-> This calls "SumCallback"

|--> This calls the "callback"

|---> This calls console.log(result)

|---> return "result"

|--> return the value of the "callback" (result)

|-> return the value of "SumCallback" (result)