Sum of an Array

There is no native sum() function on JavaScript arrays, so the sum has to be calculated by hand somehow. There is the method reduce() on array, though.

The reduce() method applies a function against an accumulator and each element in the array (from left to right) to reduce it to a single value.

So, to sum the values of an array, we can simply use reduce() in a way like this (ES6 Syntax):

const array = [1, 2, 3, 4]
const arraySum = array.reduce((sum, value) => sum + value, 1)
console.log(arraySum) // -> 10

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