Average or Sum the values in an array using Javascript (and Underscore.js)

avg_or_sum_array_with_js.js

// requires Underscore.js
// uses jQuery style funciton declaration (if you aren't using jQuery, simply re-arrange the declaration)

function sum(arr) { 
  // returns the sum total of all values in the array
  return _.reduce(arr, function(memo, num) { return memo + num}, 0); 
}

function average(arr) {
  // returns the average of all values in the array
  return sum(arr) / arr.length; 
}

this is cool