AngularJS / javascript special sort order of javascript objects

Question

I have e.g. an array like this:

var myArray = [];

var item1 = {
    start: '08:00',
    end: '09:30'
}
var item2 = {
    start: '10:00',
    end: '11:30'
}
var item3 = {
    start: '12:00',
    end: '14:30'
}
var item4 = {
    start: '16:00',
    end: '18:25'
}
var item5 = {
    start: '19:00',
    end: '21:25'
}

myArray.push(item1);
myArray.push(item2);
myArray.push(item3);
myArray.push(item4);

After sorting the order should look like this

[item1, item2, item5, item4, item3]

So the items with start- time before 12:00 should be ascending and the items with start time after or equal 12:00 sould be in reverse order.

I use AngularJS to iterate over the items:

<div ng-repeat="item in $scope.myArray" | orderBy:myOrderFunction? ...

and I would need the above order for ng-repeat. Is there a possibiliy to do this (in a performant way)?

Answer 1

That's quite weird, to be honest. However, this should do it:

function wiggleTime(time) {
  var t = 60 * parseInt(time.substr(0, 2), 10) + parseInt(time.substr(3), 10);
  return (t >= 720) ? 2160 - t : t;
}

function wiggleComparator(a, b) {
  var aa = wiggleTime(a.start);
  var bb = wiggleTime(b.start);
  return aa - bb;
};
console.log(myArray.sort(wiggleComparator).map(function(o) { return o.start; }));
// ["08:00", "10:00", "19:00", "16:00", "12:00"]

To make it more performant, you could pre-wiggle the time and store it into the structure, so you wiggle it only once per element rather than twice per each tested pair.

Answer 2

I have add a sort function in your code

myArray.sort(function(a, b) {
if(a.start.split(':')[0]>=12)
return a.start.split(':')[0] + b.start.split(':')[0];
else
return a.start.split(':')[0] - b.start.split(':')[0]
});

      <div ng-app>
        <div ng-controller="TodoCtrl">
        <div ng-repeat="item in myArray" >
           {{item.start}}
        </div>
        </div>
      </div>

 function TodoCtrl($scope) {
    var myArray = [];

   var item1 = {
     start: '08:00',
     end: '09:30'
    }
   var item2 = {
       start: '10:00',
       end: '11:30'
   }
   var item3 = {
       start: '12:00',
       end: '14:30'
   }
   var item4 = {
       start: '16:00',
       end: '18:25'
   }
   var item5 = {
       start: '19:00',
       end: '21:25'       
   }

   myArray.push(item1);
   myArray.push(item2);
   myArray.push(item3);
   myArray.push(item4);
   myArray.push(item5);
   myArray.sort(function(a, b) {
    if(a.start.split(':')[0]>=12)
      return a.start.split(':')[0] + b.start.split(':')[0];
    else
     return a.start.split(':')[0] - b.start.split(':')[0]
  });
   $scope.myArray=myArray;
   }