Javascript sort array of strings with preference

Question

I am trying to sort an array in JavaScript, but I want one specific item to always be first in the sort, and another specific item to always be last:

var Person= [{
   "Country": "Japan",
   "Name": "user1"

}, {
   "Country": "Spain",
   "Name": "user24"

}, {
   "Country": "Usa",
   "Name": "user1"

}, {
   "Country": "Brazil",
   "Name": "user1"

}];

Here is my compare function:

function compare(a,b) {
      if (a.Country< b.Country)
        return -1;
      if (a.Country> b.Country)
        return 1;
   //here aditional condition
      if(a.Country=="Spain") //condition for last item
          return 2; 
       if(a.Country=="Brazil") //condition for always in first item
          return -1; 
      return 0;
    }

I am running Person.sort(compare); to do the sort.

You need to check for the condition when b.country == "Spain" and b.country == "Brazil" as well — gengkev
– gengkev, Commented Aug 28, 2015 at 0:39
…and you need to check for those conditions before the normal comparisons. — Bergi
– Bergi, Commented Aug 28, 2015 at 0:43
Why don't you just group by country? Person.reduce(function (o, current) {o[current.Country] = (o[current.Country] || []).concat(current.Name); return o}, {}). — royhowie
– royhowie, Commented Aug 28, 2015 at 0:43

Maximillian Laumeister · Accepted Answer · 2015-08-28 00:44:07Z

3

Firstly you need to check b against those strings as well, and second of all, your special comparisons need to come before the general ones.

Working Live Demo:

function compare(a, b) {
    if (a.Country == "Spain") return 1;
    if (a.Country == "Brazil") return -1;
    if (b.Country == "Spain") return -1;
    if (b.Country == "Brazil") return 1;
    if (a.Country < b.Country) return -1;
    if (a.Country > b.Country) return 1;
    return 0;
}

var Person = [{
    "Country": "Japan",
        "Name": "user1"

}, {
    "Country": "Spain",
        "Name": "user24"

}, {
    "Country": "Usa",
        "Name": "user1"

}, {
    "Country": "Brazil",
        "Name": "user1"
}];

Person.sort(compare);
console.log(Person);

answered Aug 28, 2015 at 0:44

Maximillian Laumeister

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2 Comments

jearca Over a year ago

thanks "the order of the factors does alter the result" :)

Maximillian Laumeister Over a year ago

Hi @jearca, do you feel as if I answered your question completely? If so, please don’t forget to mark my answer as "accepted" by clicking the gray checkmark to the left. If your question hasn't been fully answered, please elaborate on what else you need to know so the community can provide you with further help! Thanks!

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