get average value

getAverage.js

//Returns the average of all values in any non-empty array.

//note that the '0' is an optionally supplied initial value. If this value is not supplied, the 0th element is used as the initial value.
const arrAvg = arr => arr.reduce((a,b) => a + b, 0) / arr.length
// arrAvg([20, 10, 5, 10]) -> 11.25


/*
notes: Finding the average value of a group of numbers is as easy as summing all of the numbers and dividing by the total number of numbers.
In this function, we first use reduce() to reduce all values in our array to a single sum. Once we have the sum we simply divide this value by the length of the array. The result is the average value which then gets returned.
*/