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

I have an array of objects like this:

// 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'},
]

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: 'B'},
   {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: 'B'},
   {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.

CodePudding user response：

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: '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);

CodePudding user response：

let 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 data = dishes.sort((a, b) => {
            if(a.category=='VEGETABLE'){
              return -1;
            }
            if (a.category > b.category) return -1;
            if (a.category < b.category) return 1;
            return a.description.localeCompare(b.description);
          });
          
console.log(data)

CodePudding user response：

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

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'}
]

dishes.sort((a, b) => {
  if (a.category == 'VEGETABLE') return -1
  if (b.category == 'VEGETABLE') return 1
  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.