Undefined array parameter with Javascript

Question

I can't see why this function is returning undefined:

function sumArray(array) {
 array.reduce(function(result, item) {
 return result + item;
 })
}
array = [1,2,3]
sumArray(array)

I've tried something similar and it works ok (below), so I'm not sure if it's specific to the parameter being an array?

function sayNumber(num) {
 return num + 1;
} 
num = 1
sayNumber(num)

• Spencer Wieczorek: Because your function sumArray doesn't return anything.
• Chris: Any function that doesn't explicitly return something returns "undefined" instead. You just invoke the array.reduce method but your not returning it so it really doesn't have anything to return

Answer 1

What you actually need is to add one more return statement.

function sumArray(array) {
 //here
 return array.reduce(function(result, item) {
 return result + item;
 });
}
array = [1,2,3];
sumArray(array);
//6

• Ivan Kalita: @safikabis, happy to help and welcome to Stack Overflow! If this or any other answer solved your problem, please, mark it as accepted.

Answer 2

The function sumArray is not returning the result from array.reduce. Insert a return before your array.reduce.

Answer 3

It returns undefined because there is no return statement for the sumArray function.

(The anonymous function you pass to reduce has one, but that is a different function).

If you want to return the result of calling array.reduce when you have to say so explicitly:

return array.reduce(etc, etc...

Answer 4

You should return the value of the function sumArray Like this:

function sumArray(array) {
 return array.reduce(function(result, item) {
 return result + item;
 })
}