Question 185532 in Javascript Question posted in
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Javascript – Sort array based on another array and add rest

I need to sort array based on another.

Arr1

const arr1 =[ 
{id: 74, name: 'Mat', type: 'bus'},
{id: 2, name: 'Johan',  type: 'plane'} 
{id: 25,  name: 'Kevin', type: 'car'},
{id: 10, name: 'Mary',  type: 'plane'},
{id: 34, name: 'Katrin',  type: 'car'}  
]

Arr2

const arr2 =[ 
{id: 25},
{id: 34},
{id: 10}, 
]  
or without id ... it does not matter 
const arr2 =["25","34", "10"]

What I want to get back is sorted array with the rest ids that is not in the second array

const arr1 =[ 
{id: 25,  name: 'Kevin', type: 'car'},
{id: 34, name: 'Katrin',  type: 'car'} 
{id: 10, name: 'Mary',  type: 'plane'},
{id: 74, name: 'Mat', type: 'bus'},
{id: 2, name: 'Johan',  type: 'plane'}  
]

I found several solutions, but no one of them deal with the rest of objects that are not in array2 (id:74 and id:2). Any suggestions?

Tags:

2

Answers


  1. 0

    Find indices of IDs and sort accordingly. You could also cache the indices in a Map, works a bit faster:

    enter image description here

    <script benchmark data-count="1000000">

  // @benchmark easy solution
{
  const arr1 =[ 
    {id: 74, name: 'Mat', type: 'bus'},
    {id: 2, name: 'Johan',  type: 'plane'},
    {id: 25,  name: 'Kevin', type: 'car'},
    {id: 10, name: 'Mary',  type: 'plane'},
    {id: 34, name: 'Katrin',  type: 'car'}  
    ];
    const arr2 =[25,34, 10];

    arr1.sort((a, b) => {
      const [idxA, idxB] = [a, b].map(what => arr2.findIndex(item => item === what.id));
      if(idxA === idxB){ // -1
        return 0;
      }
      if(idxA === -1){
        return 1;
      }
      if(idxB === -1){
        return -1;
      }
      return idxA - idxB;

    });
}

  // @benchmark optimized solution
{
    const arr1 =[ 
    {id: 74, name: 'Mat', type: 'bus'},
    {id: 2, name: 'Johan',  type: 'plane'},
    {id: 25,  name: 'Kevin', type: 'car'},
    {id: 10, name: 'Mary',  type: 'plane'},
    {id: 34, name: 'Katrin',  type: 'car'}  
    ];

    const arr2 =[25,34, 10];

    // cache indices
    const indices = arr2.reduce((map, item, idx) => map.set(item, idx), new Map);

    arr1.sort((a, b) => {
      const [idxA, idxB] = [indices.get(a.id) ?? -1, indices.get(b.id) ?? -1];

      if(idxA === idxB){ // -1
        return 0;
      }
      if(idxA === -1){
        return 1;
      }
      if(idxB === -1){
        return -1;
      }
      return idxA - idxB;

    });
}
</script>
<script src="https://cdn.jsdelivr.net/gh/silentmantra/benchmark/loader.js"></script>
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  2. 0

    This should do it.

    const 
     arr1 = [ {id: 74, name: 'Mat', type: 'bus'}, {id: 2, name: 'Johan', type: 'plane'}, {id: 25, name: 'Kevin', type: 'car'}, {id: 10, name: 'Mary', type: 'plane'}, {id: 34, name: 'Katrin', type: 'car'} ],
     
     arr2 = [25, 34, 10],
     
     getIndex = (n, a) => a.includes(n) ? a.indexOf(n) : a.length;

     sorted = arr1.sort(
        (a,b) => 
        getIndex(a.id, arr2) - getIndex(b.id, arr2)
     );

console.log( sorted );
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