Javascript arrays // reordering an array starting at a specified index while keeping the original order

Question

Having the following array :

var arr = [a,b,c,d,e];

I'm struggling to get a clean function that sorts the array based on a specified index, keeping at the same time the original order

For example, sorting the array from index 3 (so here, from "d"), would give the following :

[d,e,a,b,c]

From index 2 :

[c,d,e,a,b]

etc...

It might be obvious for some but I can't make it in my mind

Help appreciated, thx in advance

* Edit *

Is a duplicate. Here is a good one.

https://stackoverflow.com/a/7861200/102133

I don't think the word "sort" is appropriate here, as "sorting" means "reordering". Rotate maybe? — Pointy, Jan 11 '15 at 17:16
start from the index a go the end after that restart from 0 index and go to the first starting index. Try it yourself... You can use two loops for that... — eugsun, Jan 11 '15 at 17:17
http://stackoverflow.com/questions/2440700/reordering-arrays — Roko C. Buljan, Jan 11 '15 at 17:17
Curious.. how is it possible that this question is still receiving answers when it is closed as a duplicate? — Boann, Jan 11 '15 at 17:27
@Ben No. But the question has been marked as a duplicate. As far as I know, that makes it impossible for anyone to post an answer on it, yet they are. — Boann, Jan 11 '15 at 17:29
Found explanation: https://meta.stackoverflow.com/questions/252711/this-answer-was-posted-after-the-question-was-closed-how-is-that-possible — Boann, Jan 11 '15 at 17:44
@Boann Hope I'm not duplicating again on this one http://stackoverflow.com/questions/27890656/javascript-arrays-comparing-two-similars-arrays-and-getting-object-that-needs but that'd be in the end what I really look for — Ben, Jan 11 '15 at 18:38

Oleksandr T. · Accepted Answer · 2019-01-17T08:25:09.780

3

var arr = ['a','b','c','d','e'];

function reorder(data, index) {
  return data.slice(index).concat(data.slice(0, index))
};

console.log(reorder(arr, 3));
console.log(reorder(arr, 2));

edited Jan 17 '19 at 08:25

answered Jan 11 '15 at 17:22

Oleksandr T.

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score 1 · Answer 2 · answered Jan 11 '15 at 17:24

This function will do your work

var reorder = function(arr,index){
    var start = arr.slice(index); // This will return me elements from a given index
    var end = arr.slice(0,index); // This will return me elements before a given index
    return start.concat(end); // Concat 2nd array to first and return the result.
 }

Javascript arrays // reordering an array starting at a specified index while keeping the original order

2 Answers2