Sort null values based on another variable in the object

Question

I'm trying to sort a list of Objects in ascending order. But there are cases when the sort value is null and in that case, the value should be sorted alphabetically.

I tried to create the following code:

let items = [
  {
   name: 'Foo',
   Km: null
  },
  {
   name: 'Bar',
   Km: 4
  },
  {
   name: 'BarFoo',
   Km: null
  },
  {
   name: 'FooBar',
   Km: 1
  },
]

function sortNullValues(values) {

    values.sort(function (a, b) {
    if(a.Km === null) return 1
    if(b.Km === null) return -1
    if (a.Km < b.Km) return 1
        if (a.Km < b.Km) return -1
    if (a.name > b.name) return -1
        if (a.name < b.name) return 1
  })

  return values
}

console.log(sortNullValues(items))

But the null valued objects are not sorting alphabetically. https://jsfiddle.net/am7n61ou/56/

Current Output:

[
  {
   name: 'Bar',
   Km: 4
  },
  {
   name: 'FooBar',
   Km: 1
  },
  {
   name: 'Foo',
   Km: null
  },
  {
   name: 'BarFoo',
   Km: null
  }
]

Desired Output:

[
  {
   name: 'FooBar',
   Km: 1
  },
  {
   name: 'Bar',
   Km: 4
  },
  {
   name: 'BarFoo',
   Km: null
  },
  {
   name: 'Foo',
   Km: null
  }
]

Answer 1

You could first sort the null values to bottom, sort by Km ( null - null is zero) or by string.

 var array = [{ name: 'Foo', Km: null }, { name: 'Bar', Km: 4 }, { name: 'BarFoo', Km: null }, { name: 'FooBar', Km: 1 }]; array.sort((a, b) => (a.Km === null) - (b.Km === null) || a.Km - b.Km || a.name.localeCompare(b.name) ); console.log(array); 

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

Answer 2

You function always returns -1 even if both values are null. I've fixed your code. You should check for null values and return different sorting.

Corrected code:

  values.sort(function (a, b) {
    if (a.Km === null && b.Km === null) {
      if (a.name > b.name) return 1
      if (a.name < b.name) return -1
        }
    if(a.Km === null) return 1
    if(b.Km === null) return -1
    if (a.Km < b.Km) return 1
        if (a.Km < b.Km) return -1
  })