Sort an array of objects by two properties, but force one to go first

Question

I have an array of objects like this:

// dishes: [
   {category: 'LEGUME', description: 'A'},
   {category: 'VEGETABLE', description: 'N'},
   {category: 'VEGETABLE', description: 'B'},
   {category: 'VEGETABLE', description: 'A'},
   {category: 'FISH', description: 'C'},
   {category: 'LEGUME', description: 'E'},
   {category: 'LEGUME', description: 'B'},
   {category: 'LEGUME', description: 'N'},
]

I'm sorting this array with this function:

const dishes = dishes.sort((a, b) => {
            if (a.category > b.category) return -1;
            if (a.category < b.category) return 1;
            return a.description.localeCompare(b.description);
          });

The output from above is like this:

// dishes: [
   {category: 'LEGUME', description: 'A'},
   {category: 'LEGUME', description: 'B'},
   {category: 'LEGUME', description: 'E'},
   {category: 'LEGUME', description: 'N'},
   {category: 'VEGETABLE', description: 'A'},
   {category: 'VEGETABLE', description: 'B'},
   {category: 'VEGETABLE', description: 'N'},
   {category: 'FISH', description: 'C'},
]

But now I want to force one of the categories to be the first one, let's say VEGETABLE, so the output should be:

// dishes: [
   {category: 'VEGETABLE', description: 'A'},
   {category: 'VEGETABLE', description: 'B'},
   {category: 'VEGETABLE', description: 'N'},
   {category: 'LEGUME', description: 'A'},
   {category: 'LEGUME', description: 'B'},
   {category: 'LEGUME', description: 'E'},
   {category: 'LEGUME', description: 'N'},
   {category: 'FISH', description: 'C'},
]

I've tried a bunch of solutions from other questions but none worked, any suggestions? is it possible?

Thanks in advance.

[UPDATED]: my final solution, thanks to @Andrew Parks:

dishes.sort((a, b) =>
    +(b.category === "VEGETABLE") -
    +(a.category === "VEGETABLE") ||
    a.category.localeCompare(b.category) ||
    a.description.localeCompare(b.description)
);

Andrew Parks · Accepted Answer · 2022-10-09 06:32:14Z

2

The neatest way is this:

const dishes = [
   {category: 'LEGUME', description: 'A'},
   {category: 'VEGETABLE', description: 'B'},
   {category: 'FISH', description: 'C'},
   {category: 'LEGUME', description: 'E'},
   {category: 'LEGUME', description: 'B'},
   {category: 'LEGUME', description: 'N'},
];

const cmp = (a,b,c) => a[c].localeCompare(b[c]);
const cmpEq = (a,b,c,d) => (b[c]===d) - (a[c]===d);
dishes.sort((a,b) => 
  cmpEq(a,b, 'category', 'VEGETABLE') || 
  cmp(a,b, 'category') || 
  cmp(a,b, 'description')
);

console.log(dishes);

If you want any of the sorts to be in reverse order, just put a minus sign in front of the cmp().

edited Oct 9, 2022 at 6:32

answered Oct 9, 2022 at 6:19

Andrew Parks

8,1672 gold badges21 silver badges35 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ismaestro · Accepted Answer · 2022-10-09 19:26:16Z

1

You can concatenate both category and description when sorting, as follows:

const dishes = [
   {category: 'LEGUME', description: 'A'},
   {category: 'VEGETABLE', description: 'B'},
   {category: 'VEGETABLE', description: 'A'},
   {category: 'VEGETABLE', description: 'N'},
   {category: 'FISH', description: 'C'},
   {category: 'LEGUME', description: 'E'},
   {category: 'LEGUME', description: 'B'},
   {category: 'LEGUME', description: 'N'}
]

dishes.sort((a, b) => {
  if (a.category === 'VEGETABLE') return -1
  if (b.category === 'VEGETABLE') return 1
  return `${a.category}${a.description}`.localeCompare(`${b.category}${b.description}`);
});

console.log(dishes)

.as-console-wrapper { max-height:100% !important; top 0; }

edited Oct 9, 2022 at 19:26

ismaestro

8,3079 gold badges39 silver badges52 bronze badges

answered Oct 9, 2022 at 15:36

PeterKA

24.7k5 gold badges28 silver badges52 bronze badges

2 Comments

ismaestro Over a year ago

thats nice!, but now VEGETABLE is not alphabetically sorted. How would I sort that category too?

PeterKA Over a year ago

Did you not indicate an exception for it? But now I want to force one of the categories to be the first one, let's say VEGETABLE, so the output should be:...

Nick · Accepted Answer · 2022-10-09 22:55:48Z

1

You can special case the VEGETABLE value in your sort function:

const dishes = [
   {category: 'LEGUME', description: 'A'},
   {category: 'VEGETABLE', description: 'B'},
   {category: 'VEGETABLE', description: 'A'},
   {category: 'VEGETABLE', description: 'N'},
   {category: 'FISH', description: 'C'},
   {category: 'LEGUME', description: 'E'},
   {category: 'LEGUME', description: 'B'},
   {category: 'LEGUME', description: 'N'}
]

dishes.sort((a, b) => {
  res = (b.category == 'VEGETABLE') - (a.category == 'VEGETABLE')
  if (res) return res
  res = a.category.localeCompare(b.category)
  if (res) return res
  return a.description.localeCompare(b.description);
});

console.log(dishes)

.as-console-wrapper { max-height:100% !important; top 0; }

Note that sort sorts the array inplace so you don't need to assign the result from it.

edited Oct 9, 2022 at 22:55

answered Oct 9, 2022 at 6:00

Nick

147k23 gold badges67 silver badges106 bronze badges

2 Comments

ismaestro Over a year ago

Same as PeterKA. The answer is ok, but now VEGETABLE is not alphabetically sorted. How would I sort that category too?

Nick Over a year ago

@ismaestro apologies for that. I got fixated on the fact that there was only one VEGETABLE entry. I've corrected the code, but I think you've already accepted the best answer.

ismaestro · Accepted Answer · 2022-10-09 19:33:18Z

0

First compare by the difference of whether the items are of VEGETABLE or not - proceed to the rest of the sort function only if that results in 0.

const dishes = [
   {category: 'LEGUME', description: 'A'},
   {category: 'VEGETABLE', description: 'B'},
   {category: 'VEGETABLE', description: 'A'},
   {category: 'VEGETABLE', description: 'N'},
   {category: 'FISH', description: 'C'},
   {category: 'LEGUME', description: 'E'},
   {category: 'LEGUME', description: 'B'},
   {category: 'LEGUME', description: 'N'},
];
dishes.sort((a, b) => {
  const vegResult = a.category === 'VEGETABLE' - b.category === 'VEGETABLE';
  if (vegResult) return vegResult;
  if (a.category > b.category) return -1;
  if (a.category < b.category) return 1;
  return a.description.localeCompare(b.description);
});
console.log(dishes);

edited Oct 9, 2022 at 19:33

ismaestro

8,3079 gold badges39 silver badges52 bronze badges

answered Oct 9, 2022 at 5:58

CertainPerformance

373k55 gold badges354 silver badges359 bronze badges

1 Comment

ismaestro Over a year ago

Sorry your solution does not work. If I choose another category like FISH, to be the first one, and obviously I replace VEGETABLE for FISH, it does not work. In fact, a.category === 'VEGETABLE' - b.category === 'VEGETABLE' is always false.

Collectives™ on Stack Overflow

Sort an array of objects by two properties, but force one to go first

4 Answers 4

Comments

2 Comments

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

2 Comments

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related