benwells

var accounts = [
  { name: 'James Brown', msgCount: 123 },
  { name: 'Stevie Wonder', msgCount: 22 },
  { name: 'Sly Stone', msgCount: 16 },
  { name: 'Otis Redding', msgCount: 300 }  // Otis has the most messages
];

// get sum of msgCount prop across all objects in array
var msgTotal = accounts.reduce(function(prev, cur) {
  return prev + cur.msgCount;

joshcarr

function groupBy( array , f ) {
  var groups = {};
  array.forEach( function( o )
  {
    var group = JSON.stringify( f(o) );
    groups[group] = groups[group] || [];
    groups[group].push( o );
  });
  return Object.keys(groups).map( function( group )
  {

hjst

function format_time(date_obj) {
  // formats a javascript Date object into a 12h AM/PM time string
  var hour = date_obj.getHours();
  var minute = date_obj.getMinutes();
  var amPM = (hour > 11) ? "pm" : "am";
  if(hour > 12) {
    hour -= 12;
  } else if(hour == 0) {
    hour = "12";
  }