Question

I’d like to sort by time,day.
Here is my attempt:

var days = new Array();
var days['SU'] = 0;
var days['MO'] = 1;
var days['TU'] = 2;
var days['WE'] = 3;
var days['TH'] = 4;
var days['FR'] = 5;
var days['SA'] = 6;

events.sort(function(a, b)
{
    if(a['day'] != b['day'])
    {
        return (days[a['day']] < days[b['day']]) ? 1 : -1;
    }
    else if(a['time'] != b['time'])
    {
        return (a['time'] < a['time']) ? 1 : -1;
    }
    else
        return 0;
);

It’s not tested, but am I doing it correct?
(Time asc, days asc) Mon 8am, Tues 8am, Mon 9pm is the order I’m looking for.

Cheers.

events[0]['day'] = 'MO';
events[0]['time'] = 8;
events[1]['day'] = 'MO';
events[1]['time'] = 21;
events[2]['day'] = 'TU';
events[2]['time'] = 8;

My solution which seems to work thanks to @T.J. Crowder

events = new Array();
events[0] = new Array();
events[0]['day'] = 'MO';
events[0]['time'] = 8;
events[1] = new Array();
events[1]['day'] = 'MO';
events[1]['time'] = 21;
events[2] = new Array();
events[2]['day'] = 'TU';
events[2]['time'] = 8;

var days = {
    'SU': 0,
    'MO': 1,
    'TU': 2,
    'WE': 3,
    'TH': 4,
    'FR': 5,
    'SA': 6
};

events.sort(function(a, b)
{
    if (a.time != b.time)
    {
        return a.time - b.time;
    }
    else if (a.day != b.day)
    {
        return days[a.day] - days[b.day];
    }
    else
    {
        return 0;
    }
});

Condensed:

events.sort(function(a, b)
{
    return a.time != b.time
       ? a.time - b.time
       : days[a.day] - days[b.day];
});

Answer 1

Your fundamental approach is sound. A few notes:

1. You’re not using days as an array, so I wouldn’t make it an array. Instead:

   var days = {
       'SU': 0,
       'MO': 1,
       'TU': 2,
       'WE': 3,
       'TH': 4,
       'FR': 5,
       'SA': 6
   };
   

   Also, you don’t need those quotes since none of those strings is a keyword, so:

   var days = {
       SU: 0,
       MO: 1,
       TU: 2,
       WE: 3,
       TH: 4,
       FR: 5,
       SA: 6
   };
   

   …but you may choose to keep them as a style thing, or to defend against adding ones that are keywords later.

2. You don’t have to use the bracketed notation to look up a property (a['day']) unless the string you’re using for the property name is dynamic or the property name is a reserved word. day is neither, so you can use the simpler dotted notation (a.day).

3. There is no elseif in JavaScript; use else if.

4. You can simplify this:

   return (days[a['day']] < days[b['day']]) ? 1 : -1;
   

   to

   return days[a.day] - days[b.day];
   

   ..and you may be able to do something similar with your time values, but I don’t know what they are, so… now that you’ve posted them, I do, and you can.

5. Strongly recommend always using braces, not just when you “need” them. (None of your three branches actually needs them, but you’re only using them on two.)

6. You’ve compared a['time'] to a['time] rather than b['time'] when checking for equality.

7. You haven’t ended your function (missing })

8. Since you can just subtract your time values, you don’t need your final equality check.

   So:

   events.sort(function(a, b)
   {
       if (a.day != b.day)
       {
           return days[a.day] - days[b.day];
       }
       else
       {
           return a.time - b.time;
       }
   });
   

   …or you can condense it further:

   events.sort(function(a, b)
   {
       return (a.day != b.day
              ? days[a.day] - days[b.day]
              : a.time - b.time);
   });
   

Live example