JavaScript: Move an array element from one position to another

Last update on May 30 2022 10:00:36 (UTC/GMT +8 hours)

JavaScript Array: Exercise-38 with Solution

Write a JavaScript function to move an array element from one position to another.

Test Data:
console.log(move([10, 20, 30, 40, 50], 0, 2));
[20, 30, 10, 40, 50]
console.log(move([10, 20, 30, 40, 50], -1, -2));
[10, 20, 30, 50, 40]

Pictorial Presentation:

JavaScript: Move an array element from one position to another

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript function to move an array element from one position to another.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function move(arr, old_index, new_index) {
    while (old_index < 0) {
        old_index += arr.length;
    }
    while (new_index < 0) {
        new_index += arr.length;
    }
    if (new_index >= arr.length) {
        var k = new_index - arr.length;
        while ((k--) + 1) {
            arr.push(undefined);
        }
    }
     arr.splice(new_index, 0, arr.splice(old_index, 1)[0]);  
   return arr;
}

console.log(move([10, 20, 30, 40, 50], 0, 2));

console.log(move([10, 20, 30, 40, 50], -1, -2));

Sample Output:

[20,30,10,40,50]
[10,20,30,50,40]

Flowchart:

ES6 Version:

function move(arr, old_index, new_index) {
    while (old_index < 0) {
        old_index += arr.length;
    }
    while (new_index < 0) {
        new_index += arr.length;
    }
    if (new_index >= arr.length) {
        let k = new_index - arr.length;
        while ((k--) + 1) {
            arr.push(undefined);
        }
    }
     arr.splice(new_index, 0, arr.splice(old_index, 1)[0]);  
   return arr;
}

console.log(move([10, 20, 30, 40, 50], 0, 2));

console.log(move([10, 20, 30, 40, 50], -1, -2));

Live Demo :

See the Pen JavaScript - Move an array element from one position to another-array-ex- 38 by w3resource (@w3resource) on CodePen.

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JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04