Question 52762 in Javascript Question posted in
A very good W3school tutorial can be found here.

sorting an array of objects from smallest to biggest while throwing all null values at the end of the array – Javascript

I wanna sort this array in ascending order based on the max ranking in the objects, but there are certain objects that have null values for ranking , I want to throw the objects with null at the end, here is what I tried but it’s not working , when I am logging the first 10 ranks of the sorted array I still have undefined values

async function getLive(){
    let response= await fetch('https://tennisapi1.p.rapidapi.com/api/tennis/events/live', options)
    let json= await response.json()
    for(let i=0; i<10;i++){
        console.log(json.events[i].awayTeam.ranking<json.events[i].homeTeam.ranking?json.events[i].awayTeam.ranking:json.events[i].homeTeam.ranking)
    }
    json.events.sort((a, b) => {
      let x=1000000  
      let r1 = Math.min(a.awayTeam.ranking , a.homeTeam.ranking)
          
      if(r1===null){
        r1=x
      }
      x+=1
      let r2 = b.awayTeam.ranking < b.homeTeam.ranking ? b.awayTeam.ranking : b.homeTeam.ranking;
      if(r2===null){
        r2=x
      }
      x++
      return r1 - r2;
    });
    live=json.events
    console.log('-----------------------------')
    for(let i=0; i<10;i++){
        console.log(Math.min(live[i].awayTeam.ranking ,live[i].homeTeam.ranking))
    }

when I log here is what I get, why are the Nan values there it makes no sense

121
NaN
NaN
73
192
295
360
394
473
475

Tags:

3

Answers


  1. 0

    I don’t know what your data looks like, but here is an example with a simple array:

    const array = [1, 4, 6, 2, 7, null, 2, 5, 10, null, 3]

array.sort((a, b) => {
  if (a === b) return 0
  if (a === null) return 1
  if (b === null) return -1
  return a - b
})

console.log(array)
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  2. 0

    There is a neat trick to make this simple. You can just coalesce null values as -Infinity!

    values.sort(
    (a, b) => (b ?? -Infinity) - (a ?? -Infinity)
);

    This way, any null (or undefined) value will be replaced by the smallest possible value, hence it goes to the very end of the array.

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  3. 0

    An alternative solution would be to first partition the array into "rated" and "unrated" items based on whether rating is null, then sort the rated items, and finally concatenating the two using the spread operator:

    const array = [
  {rating: 66},
  {rating: null},
  {rating: 42},
  {rating: 101},
]
const rated = array.filter(x => x.rating !== null)
const unrated = array.filter(x => x.rating === null)
rated.sort((a, b) => a.rating - b.rating)
const sorted = [...rated, ...unrated] // alternatively you could also append unrated to rated after sorting if you don't want to copy rated here
console.log(sorted)
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