Get an item in an array to first position according to a condition

Question

Hey I have the following array :

var ar = [{id: "F"}, {id: "G"}, {id: "Z"}, {id: "ZZ"}]

I would like to move the one with the id equals to ZZ to the first position in the array. I know how to do it using several different functions, but I was wondering if there was an elegant solution to do it (lodash, ...)

You can refer following post. Its reverse but should help: http://stackoverflow.com/questions/42479079/move-a-particular-value-object-in-array-to-end/42479198#42479198 — Rajesh, Mar 21 '17 at 12:21

score 2 · Accepted Answer · answered Mar 21 '17 at 12:19

2

You could use unshift() to add to start of array and splice() and findIndex() to get object by id.

var arr = [{id: "F"}, {id: "G"}, {id: "Z"}, {id: "ZZ"}]
arr.unshift(arr.splice(arr.findIndex(e => e.id == "ZZ"), 1)[0])

console.log(arr)

answered Mar 21 '17 at 12:19

Nenad Vracar

118,580
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score 1 · Answer 2 · answered Mar 21 '17 at 12:17

1

var ar = [{
  id: "F"
}, {
  id: "G"
}, {
  id: "Z"
}, {
  id: "ZZ"
}];
ar.sort(function(a, b) {
  if (a.id === "ZZ") {
    return -1;
  }
  if (b.id === "ZZ") {
    return 1;
  }
  return 0;
});
console.log(ar);

How about sorting it?

answered Mar 21 '17 at 12:17

blackmiaool

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I have answer a post in a similar fashion: http://stackoverflow.com/a/42479198/3783478 – Rajesh Mar 21 '17 at 12:19
`Array#sort` is not guaranteed to be stable, so this could result in all the elements other than `ZZ` being in a completely new order from where they started. – JLRishe Mar 21 '17 at 13:54
Aye, just for matching the word "elegant" in the question. :) @JLRishe – blackmiaool Mar 21 '17 at 13:55
@blackmiaool I don't consider a solution that might produce the wrong result to be "elegant". – JLRishe Mar 21 '17 at 14:02
@JLRishe Those elegant es6 code can't even run in some old browswers. – blackmiaool Mar 21 '17 at 14:06

Get an item in an array to first position according to a condition

2 Answers2