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Active reading [<https://en.wikipedia.org/wiki/MacOS_High_Sierra> <https://en.wikipedia.org/wiki/ECMAScript#6th_Edition_%E2%80%93_ECMAScript_2015>]. More representative link text.
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Peter Mortensen
Peter Mortensen

Immutable insertion

Using the splice method is surely the best answer if you need to insert into an array in-place.

However, if you are looking for an immutable function that returns a new updated array instead of mutating the original array on insert, you can use the following function.

function insert(array, index) {
  const items = Array.prototype.slice.call(arguments, 2);

  return [].concat(array.slice(0, index), items, array.slice(index));
}

const list = ['one', 'two', 'three'];

const list1 = insert(list, 0, 'zero'); // Insert single item
const list2 = insert(list, 3, 'four', 'five', 'six'); // Insert multiple
 

console.log('Original list: ', list);
console.log('Inserted list1: ', list1);
console.log('Inserted list2: ', list2);

Note: This is a pre-ES2015ES6 way of doing it, so it works for both older and newer browsers.

If you're using ES6 then you can try out rest parameters too; see this answer answer.

Immutable insertion

Using splice method is surely the best answer if you need to insert into an array in-place.

However, if you are looking for an immutable function that returns a new updated array instead of mutating the original array on insert, you can use the following function.

function insert(array, index) {
  const items = Array.prototype.slice.call(arguments, 2);

  return [].concat(array.slice(0, index), items, array.slice(index));
}

const list = ['one', 'two', 'three'];

const list1 = insert(list, 0, 'zero'); // Insert single item
const list2 = insert(list, 3, 'four', 'five', 'six'); // Insert multiple
 

console.log('Original list: ', list);
console.log('Inserted list1: ', list1);
console.log('Inserted list2: ', list2);

Note: This is a pre-ES2015 way of doing it so it works for both older and newer browsers.

If you're using ES6 then you can try out rest parameters too; see this answer.

Immutable insertion

Using the splice method is surely the best answer if you need to insert into an array in-place.

However, if you are looking for an immutable function that returns a new updated array instead of mutating the original array on insert, you can use the following function.

function insert(array, index) {
  const items = Array.prototype.slice.call(arguments, 2);

  return [].concat(array.slice(0, index), items, array.slice(index));
}

const list = ['one', 'two', 'three'];

const list1 = insert(list, 0, 'zero'); // Insert single item
const list2 = insert(list, 3, 'four', 'five', 'six'); // Insert multiple

console.log('Original list: ', list);
console.log('Inserted list1: ', list1);
console.log('Inserted list2: ', list2);

Note: This is a pre-ES6 way of doing it, so it works for both older and newer browsers.

If you're using ES6 then you can try out rest parameters too; see this answer.

Source Link
kabirbaidhya
kabirbaidhya

Immutable insertion

Using splice method is surely the best answer if you need to insert into an array in-place.

However, if you are looking for an immutable function that returns a new updated array instead of mutating the original array on insert, you can use the following function.

function insert(array, index) {
  const items = Array.prototype.slice.call(arguments, 2);

  return [].concat(array.slice(0, index), items, array.slice(index));
}

const list = ['one', 'two', 'three'];

const list1 = insert(list, 0, 'zero'); // Insert single item
const list2 = insert(list, 3, 'four', 'five', 'six'); // Insert multiple


console.log('Original list: ', list);
console.log('Inserted list1: ', list1);
console.log('Inserted list2: ', list2);

Note: This is a pre-ES2015 way of doing it so it works for both older and newer browsers.

If you're using ES6 then you can try out rest parameters too; see this answer.

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