Sorting with multiple conditions

Question

I have an array of objects like so:

[
    { 
        required: false,
        sort: 1
    },
    { 
        required: true,
        sort: 2
    },
    { 
        required: false,
        sort: 3
    },
]

I want to sort it by required DESC, sort ASC. How do you do this?

The result I am looking for is:

[
    { 
        required: true,
        sort: 2
    },
    { 
        required: false,
        sort: 1
    },  
    { 
        required: false,
        sort: 3
    },
]

Currently tried with this, which doesnt work. It correctly puts required first, but then ignores sort for the required items:

arr.sort((a, b) => {
    if (a.required) return -1

    return a.sort - b.sort
})

Whenever you're sorting on multiple fields you must always be able to break ties. In your `if` statement, you're not handling the case when `a.required` is equal to or the case when `b.required` is set but not `a.required`. — Matthew, Jun 02 '22 at 15:40

score 2 · Accepted Answer · answered Jun 02 '22 at 15:43

You can subtract the second required (2) from the first (1) when comparing. If they are the same value, you can logical-OR the left (1) and right (2) sort values.

const data = [
  { required: false , sort: 1 },
  { required: true  , sort: 2 },
  { required: false , sort: 3 },
];

const sorted = data.sort((
  { required: r1, sort: s1 },
  { required: r2, sort: s2 }
) => r2 - r1 || s1 - s2);

console.log(sorted);

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

In JavaScript, subtracting booleans results in an integer value that is useful for sorting.

true  - true   //  0 (no change)
true  - false  // +1 (sink to bottom)
false - true   // -1 (float to top)
false - false  //  0 (no change)

Sorting with multiple conditions

1 Answers1