gistfile1.js

var RecordSortingService = [function() {
  var sortables = [];
  
  function getSortable(context) {
    var sortable = sortables.filter(function(sortable) {
      return sortable.context == context;
    })[0];
    
    if (!sortable) {
      sortable = new Sortable(context);
      sortables.push(sortable);
    }
    
    return sortable;
  }
  
  function Sortable(context) {
    this.context = context;
    
    // Field to sort by
    this.field = null;
    
    // Order
    this.order = true;
  };
  
  this.sortBy = function(context, field) {
    var sortable = getSortable(context);
    
    sortable.field = field;
  };
  
  this.getSorting = function(context) {
    var sortable = getSortable(context);
    
    return sortable.field;
  };
  
  this.changeOrder = function(context) {
    var sortable = getSortable(context);
    
    sortable.order = !sortable.order;
  };
}];

angular.module('App').service('RecordSortingService', RecordSortingService);


// Use it like this
RecordSortingService.sortBy('foo', 'date');
RecordSortingService.changeOrder('foo');
RecordSortingService.getSorting('foo'); // "date"

RecordSortingService.sortBy('bar', 'type'); // won't affect 'foo' sorting