Moving an item to the top of an array in JavaScript/Vue.js: A simple guide

Question

Moving an item to the top of an array in JavaScript/Vue.js: A simple guide

const a = [{
    "iso2": "KH",
    "countryName": "Cambodia",
    "nationality": "Cambodian"
},
{
    "iso2": "KI",
    "countryName": "Kiribati",
    "nationality": "I-Kiribati"
},
{
    "iso2": "KM",
    "countryName": "Comoros",
    "nationality": "Comoran, Comorian"
},
{
    "iso2": "KN",
    "countryName": "Saint Kitts and Nevis",
    "nationality": "Kittitian or Nevisian"
}];

I have an array retrieved from a Get API list and I want to rearrange it so that the object with iso2 = KN is moved to the top of the list to match the select list options. I am aware of using push and unshift methods for this purpose, but I am wondering if there is a simpler way to achieve this reordering?

javascript vue.js

Answer 1

Answer №1

If you only need to reposition a specific element at the beginning of an array without sorting the entire array, there are efficient ways to achieve this.

One method is to identify the index of the desired element and then swap it with the first element in the array.

const arr = [{
"code": "A",
"name": "Alpha"
},
{
"code": "B",
"name": "Beta"
},
{
"code": "C",
"name": "Charlie"
},
{
"code": "D",
"name": "Delta"
}];

let idx = arr.findIndex(e => e.code === 'C');

arr[0] = (_=arr[idx], arr[idx] = arr[0],_);
console.log(arr)

Alternatively, you can remove the element using Array.splice and then add it back to the beginning.

const arr = [{
"code": "A",
"name": "Alpha"
},
{
"code": "B",
"name": "Beta"
},
{
"code": "C",
"name": "Charlie"
},
{
"code": "D",
"name": "Delta"
}];

let idx = arr.findIndex(e => e.code === 'C');
e = arr.splice(idx, 1);
arr.unshift(...e);
console.log(arr)

Answer 2

If you only need to reposition a specific element at the beginning of an array without sorting the entire array, there are efficient ways to achieve this.

One method is to identify the index of the desired element and then swap it with the first element in the array.

const arr = [{
"code": "A",
"name": "Alpha"
},
{
"code": "B",
"name": "Beta"
},
{
"code": "C",
"name": "Charlie"
},
{
"code": "D",
"name": "Delta"
}];

let idx = arr.findIndex(e => e.code === 'C');

arr[0] = (_=arr[idx], arr[idx] = arr[0],_);
console.log(arr)

Alternatively, you can remove the element using Array.splice and then add it back to the beginning.

const arr = [{
"code": "A",
"name": "Alpha"
},
{
"code": "B",
"name": "Beta"
},
{
"code": "C",
"name": "Charlie"
},
{
"code": "D",
"name": "Delta"
}];

let idx = arr.findIndex(e => e.code === 'C');
e = arr.splice(idx, 1);
arr.unshift(...e);
console.log(arr)

Answer 3

Answer №2

To rearrange the array according to your preference, utilize Array.sort.

const countries = [{
    "iso2": "KH",
    "countryName": "Cambodia",
    "nationality": "Cambodian"
  },
  {
    "iso2": "KI",
    "countryName": "Kiribati",
    "nationality": "I-Kiribati"
  },
  {
    "iso2": "KM",
    "countryName": "Comoros",
    "nationality": "Comoran, Comorian"
  },
  {
    "iso2": "KN",
    "countryName": "Saint Kitts and Nevis",
    "nationality": "Kittitian or Nevisian"
  }
];

countries.sort((item) => item.iso2 === 'KN' ? -1 : 1);

console.log(countries);

Answer 4

To rearrange the array according to your preference, utilize Array.sort.

const countries = [{
    "iso2": "KH",
    "countryName": "Cambodia",
    "nationality": "Cambodian"
  },
  {
    "iso2": "KI",
    "countryName": "Kiribati",
    "nationality": "I-Kiribati"
  },
  {
    "iso2": "KM",
    "countryName": "Comoros",
    "nationality": "Comoran, Comorian"
  },
  {
    "iso2": "KN",
    "countryName": "Saint Kitts and Nevis",
    "nationality": "Kittitian or Nevisian"
  }
];

countries.sort((item) => item.iso2 === 'KN' ? -1 : 1);

console.log(countries);

Answer 5

Answer №3

Give this code a shot:


let information = [
      {
        iso2: "KH",
        countryName: "Cambodia",
        nationality: "Cambodian"
      },
      {
        iso2: "KI",
        countryName: "Kiribati",
        nationality: "I-Kiribati"
      },
      {
        iso2: "KM",
        countryName: "Comoros",
        nationality: "Comoran, Comorian"
      },
      {
        iso2: "KN",
        countryName: "Saint Kitts and Nevis",
        nationality: "Kittitian or Nevisian"
      }
    ];

    let selection = "KN";
    information.sort((x, y) => (x.iso2 == selection ? -1 : y.iso2 == selection ? 1 : 0));
    console.log(information);

Answer 6

Give this code a shot:


let information = [
      {
        iso2: "KH",
        countryName: "Cambodia",
        nationality: "Cambodian"
      },
      {
        iso2: "KI",
        countryName: "Kiribati",
        nationality: "I-Kiribati"
      },
      {
        iso2: "KM",
        countryName: "Comoros",
        nationality: "Comoran, Comorian"
      },
      {
        iso2: "KN",
        countryName: "Saint Kitts and Nevis",
        nationality: "Kittitian or Nevisian"
      }
    ];

    let selection = "KN";
    information.sort((x, y) => (x.iso2 == selection ? -1 : y.iso2 == selection ? 1 : 0));
    console.log(information);

Answer 7

Answer №4

To place the last object at the top, you can easily reverse your array using the a.reverse(); method.

Answer 8

To place the last object at the top, you can easily reverse your array using the a.reverse(); method.

Moving an item to the top of an array in JavaScript/Vue.js: A simple guide

Answer №1

Answer №2

Answer №3

Answer №4

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