javascript sort sparse array keep indexes

Question

What is the best method to sort a sparse array and keep the elements on the same indexes? For example:

a[0] = 3, 
a[1] = 2, 
a[2] = 6,
a[7] = 4,
a[8] = 5,
         


        

Answer 1

// Update for your needs ('position' to your key).

function updateIndexes( list ) {

    list.sort( ( a, b ) => a.position - b.position )

    list.forEach( ( _, index, arr ) => {

        arr[ index ].position = index

    } )

}

var myList = [
   { position: 8 },
   { position: 5 },
   { position: 1 },
   { position: 9 }
]

updateIndexes( myList )

// Result:

var myList = [
   { position: 1 },
   { position: 2 },
   { position: 3 },
   { position: 4 }
]