Javascript sorting with two properties

Question

I'm struggling with sorting two levels. The logic is as follows. If any of the objects have a status, return the most recent object with a status. If none of the objects have a status, return the most recent object without a status.

var apps = [
  { status: 'PASS', 
    date_created: Thu Sep 03 2015 17:24:45 GMT-0700 (PDT)
  },
  { status: 'FAIL',
    date_created: Thu Sep 02 2015 17:24:45 GMT-0700 (PDT),
  },
  { status: '',
    date_created: Thu Sep 03 2015 17:24:45 GMT-0700 (PDT),
  }
]

var desired_result = [{ status: 'PASS', 
    date_created: Thu Sep 03 2015 17:24:45 GMT-0700 (PDT)
  }]

var apps_2 = [
  { status: '', 
    date_created: Thu Sep 03 2015 17:24:45 GMT-0700 (PDT)
  },
  { status: '',
    date_created: Thu Sep 02 2015 17:24:45 GMT-0700 (PDT),
  },
  { status: '',
    date_created: Thu Sep 01 2015 17:24:45 GMT-0700 (PDT),
  }
]

var desired_resul2 = [{ status: '', 
    date_created: Thu Sep 03 2015 17:24:45 GMT-0700 (PDT)
  }]

I've tried

var sorted = _.sort_by(apps, function (x) { x.date_updated });

I've also looked a few other SO questions but can't keep the objects in place after the first sort.

Is `date_created` a String? and there is no such function called `_.sort_by` — thefourtheye, Sep 04 '15 at 00:33
*If any of the objects have a status* - Can you please explain this clearly? All the data in your example have `status` — thefourtheye, Sep 04 '15 at 00:34
@thefourtheye or I could return it as null instead of an empty string if that's easier — user2954587, Sep 04 '15 at 00:37

sic1 · Accepted Answer · 2015-09-04T00:55:26.580

2

If I understand your question correctly, here is what you are looking for. http://jsfiddle.net/whxu5sea/3/

You need to filter the elements to ensure they have a status of ANY kind. Then sort them by date, earliest first. Then get that first value. In my example I assumed the dates where strings, but still should work.

var apps = [
  { status: 'PASS', 
    date_created: 'Thu Sep 03 2015 17:24:45 GMT-0700 (PDT)'
  },
  { status: 'FAIL',
    date_created: 'Thu Sep 02 2015 17:24:45 GMT-0700 (PDT)',
  },
  { status: '',
    date_created: 'Thu Sep 01 2015 17:24:45 GMT-0700 (PDT)',
  }
];

var x;
var arr = _.filter(apps, function(data) {
    return !!data.status.length;
});

x = _.chain( arr.length ? arr : apps )
    .sortBy(function(data) {
        return new Date(data.date_created).getTime();
    }).last().value();

console.log( x );

To check if it works when no status is provided: http://jsfiddle.net/whxu5sea/4/

I hope this helps. LMK if any further clarification is needed.

EDIT: Updated to get NEWEST element (last).

edited Sep 04 '15 at 00:55

answered Sep 04 '15 at 00:46

sic1

486
3
8

Apparently I only read part of your question, sorry! Working on it handling both cases. – sic1 Sep 04 '15 at 00:49
Fixed to handle both cases. – sic1 Sep 04 '15 at 00:55
very close! it fails to sort by date for multiple statuses https://jsfiddle.net/ts6c9sxL/ – user2954587 Sep 04 '15 at 00:58
@user2954587I just did one more update that now uses `last` instead. I think it should do it for you. Please confirm before I head home :) – sic1 Sep 04 '15 at 00:59
confirmed! thanks for this, I was pulling out my hair. Go home :) – user2954587 Sep 04 '15 at 01:00

score 1 · Answer 2 · edited May 23 '17 at 12:06

Here is a simple solution that iterates just once through apps, without a filtering step. See here for a jsfiddle.

The concept is that, if status is falsy, its date is converted into a negative number that retains the correct sort order among all falsy elements, but makes all falsy elements have a lower sort order than all non-falsy ones.

We convert the falsy element dates by subtracting 8640000000000001, which is (the maximimum millis in a Date, plus one).

var x = _.chain(apps).sortBy(function(x) {
      var date = new Date(x.date_created).getTime();
      return x.status ? date : date - 8640000000000001;
    }).last().value();

console.log( x );

Javascript sorting with two properties

2 Answers2