javascript how sort array of objects by two rule? [duplicate]

Question

I have a list of object like this:

 [
      {"groups":["aaa"]},
      {"groups":["bbb"]},
      {"groups":["ccc"]},
      {"groups":["ddd"]},
      {"groups":["eee"]},
      {"groups":["fff"]},
      {"groups":["ggg"]},
      {"groups":["hhh"]},
      {"groups":["iii"]},
      {"groups":["mmm", "mmm"]}
      {"groups":["lll", "lll"]}
];

i want put all object with more that one groups at the end of the list in alphabetical order and keep the others with one groups, at beginning of the list without change the original order.

This is my code

var list = [
  {"groups":["aaa"]},
  {"groups":["bbb"]},
  {"groups":["ccc"]},
  {"groups":["ddd"]},
  {"groups":["eee"]},
  {"groups":["fff"]},
  {"groups":["ggg"]},
  {"groups":["hhh"]},
  {"groups":["iii"]},
  {"groups":["mmm", "mmm"]},
  {"groups":["lll", "lll"]}
];

list.sort(function(a, b){
        var aIsGroup = (a.groups.length > 1);
        var bIsGroup = (b.groups.length > 1);

        if (aIsGroup && !bIsGroup) {
            return 1;
        } else if (!aIsGroup && bIsGroup) {
            return -1;
        } else if(aIsGroup && bIsGroup){
            return a.groups[0].toLowerCase().localeCompare(b.groups[0].toLowerCase());
        }
        return 0;
});

console.log(list);

You can see in the snippet the current output, but the expected output is:

[
  {
    "groups": [
      "aaa"
    ]
  },
  {
    "groups": [
      "bbb"
    ]
  },
  {
    "groups": [
      "ccc"
    ]
  },
  {
    "groups": [
      "ddd"
    ]
  },
  {
    "groups": [
      "eee"
    ]
  },
  {
    "groups": [
      "fff"
    ]
  },
  {
    "groups": [
      "ggg"
    ]
  },
  {
    "groups": [
      "hhh"
    ]
  },
  {
    "groups": [
      "iii"
    ]
  },
  {
    "groups": [
      "lll",
      "lll"
    ]
  },
  {
    "groups": [
      "mmm",
      "mmm"
    ]
  }
]

jonatjano · Accepted Answer · 2018-08-30 08:22:03Z

0

as @deceze said in comment

Javascript's sort doesn't promise a stable sorting. Any elements that are "equal" have an undefined order. See the duplicate for implementing a stable sort

but you can do this to keep them in the same order as their original order (a stable sort)

var list = [
  {"groups":["aaa"]},
  {"groups":["bbb"]},
  {"groups":["ccc"]},
  {"groups":["mmm", "mmm"]},
  {"groups":["ddd"]},
  {"groups":["fff"]},
  {"groups":["eee"]},
  {"groups":["ggg"]},
  {"groups":["hhh"]},
  {"groups":["iii"]},
  {"groups":["lll", "lll"]}
];

list.sort(function(a, b){
        var aIsGroup = (a.groups.length > 1);
        var bIsGroup = (b.groups.length > 1);

        if (aIsGroup && !bIsGroup) {
            return 1;
        } else if (!aIsGroup && bIsGroup) {
            return -1;
        } else if(aIsGroup && bIsGroup) {
            return a.groups[0].toLowerCase().localeCompare(b.groups[0].toLowerCase());
        }
        // keep in the same order
        return (list.indexOf(a) < list.indexOf(b)) ? -1 : 1;
});

console.log(list);

edited Aug 30, 2018 at 8:22

answered Aug 30, 2018 at 8:14

jonatjano

3,7681 gold badge17 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

deceze Over a year ago

I'm not sure the criterion is to sort them lexically, but rather they should retain their original order (i.e. stable sort).

jonatjano Over a year ago

@deceze you may be correct need to ask op

jonatjano Over a year ago

@deceze rereading the question you're correct

ar099968 Over a year ago

@deceze, thanks but i want the alphabetical order only if (a.groups.length > 1) && (b.groups.length > 1)

jonatjano Over a year ago

@ar099968 edited ;) fff and eee are mixed because I mixed them when declaring array to show no lexical on monoelement

Collectives™ on Stack Overflow

javascript how sort array of objects by two rule? [duplicate]

1 Answer 1

5 Comments