在数组中，如何使用.sort（）根据一个属性将另一个属性排序的对象组合在一起？

Question

Using Javascripts .sort(), I have a list of objects that have a 'category' property and a 'subcategory' property. So far I have the list sorted by category using item1.category().localeCompare(item2.category()) but within each category group I want to have the objects sorted by subcategory.

So far my array sorts into something like this:

[
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat2'}
]

Whereas I need it to be like this:

[
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat2'}
]

Also I can only use one sort() and can't do anything outside of it as it's being passed as a param to another function.

Answer 1

Just add an additional predicate to your sort function:

const arr = [ 
  { "field1": "a2", "field2": "b2" },  
  { "field1": "a1", "field2": "b2" },
  { "field1": "a1", "field2": "b1" }
];

arr.sort((a,b) => {
  return a.field1.localeCompare(b.field1) || a.field2.localeCompare(b.field2);
});
// [ {"field1":"a1","field2":"b1"},
//   {"field1":"a1","field2":"b2"},
//   {"field1":"a2","field2":"b2"}]

Answer 2

You could add another localeCompare on the subcategory, eg:

arr.sort(function (a,b) {
    return a.category.localeCompare(b.category)
        || a.subcategory.localeCompare(b.subcategory);
})

Answer 3

Just expand your sorting function.

 categories.sort(function(a, b) {
   if(a.category < b.category){
     return -1;  
   }else if(a.category > b.category){
     return 1;
   }else{
     if(a.subcategory < b.subcategory){
       return -1
     }else if(a.subcategory > b.subcategory){
       return 1;
     }
   }
 });

Look at the working fiddle here: http://jsfiddle.net/Sergey_Mell/htv6zs8g/

Answer 4

try this:

var values = [
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat1', 'subcategory':'subcat1'},
  {'category':'cat1', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat2'},
  {'category':'cat2', 'subcategory':'subcat1'},
  {'category':'cat2', 'subcategory':'subcat2'}
];
console.log(values.sort(function (a, b) {
  var tmp_a = a.category + a.subcategory;
  var tmp_b = b.category + b.subcategory;

  if (tmp_a < tmp_b) {
    return -1;
  }
  if (tmp_a > tmp_b) {
    return 1;
  }
  // a must be equal to b
  return 0;
}));

Answer 5

This works for me:

arr.sort(function(a, b) {
    if (a.category != b.category) {
        return (a.category > b.category) ? 1 : -1;
    } else {
        return (a.subcategory > b.subcategory) ? 1 : -1;
    }
    return 0;
});

It checks to see if category is different. If it is different, then it sorts by that. Else (if category is the same), it sorts by subcategory .