JavaScript: Simple Reduce Examples

JSSimpleReduceExamples.js

var miles = [{ distance: 34 }, { distance: 12 } , { distance: 1 }];
var totalDistance = miles.reduce(function(prev, item){return prev + item.distance;}, 0);

//return the total of sitting and standing chairs
var desks = [
  { type: 'sitting' },
  { type: 'standing' },
  { type: 'sitting' },
  { type: 'sitting' },
  { type: 'standing' }
];
var deskTypes = desks.reduce(function(prev, desk) {
  if (desk.type === 'sitting') prev.sitting++;
  if (desk.type === 'standing') prev.standing++;
  return prev;
}, { sitting: 0, standing: 0 });