The Array.copyWithin() method shallow copies part of an array to another location in the same array and returns it, without modifying its size.
Syntax
array.copyWithin(target, start, end)
- target(Required) - The index position to copy the elements to
- start (Optional) - The index position to start copying elements from (default is 0)
- end (Optional) - The index position to stop copying elements from (default is array.length)
Examples
Example 1: Copy the first two array elements to the last two array elements
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.copyWithin(2, 0);
output
["Banana", "Orange", "Banana", "Orange"]Example 2: Copy the first two array elements to the third and fourth position
var fruits = ["Banana", "Orange", "Apple", "Mango", "Kiwi", "Papaya"];
fruits.copyWithin(2, 0, 2);
Output:
["Banana", "Orange", "Banana", "Orange", "Kiwi", "Papaya"]More Examples
[1, 2, 3, 4, 5].copyWithin(-2);
// [1, 2, 3, 1, 2]
[1, 2, 3, 4, 5].copyWithin(0, 3);
// [4, 5, 3, 4, 5]
[1, 2, 3, 4, 5].copyWithin(0, 3, 4);
// [4, 2, 3, 4, 5]
[1, 2, 3, 4, 5].copyWithin(-2, -3, -1);
// [1, 2, 3, 3, 4]
[].copyWithin.call({length: 5, 3: 1}, 0, 3);
// {0: 1, 3: 1, length: 5}
// ES2015 Typed Arrays are subclasses of Array
var i32a = new Int32Array([1, 2, 3, 4, 5]);
i32a.copyWithin(0, 2);
// Int32Array [3, 4, 5, 4, 5]
// On platforms that are not yet ES2015 compliant:
[].copyWithin.call(new Int32Array([1, 2, 3, 4, 5]), 0, 3, 4);
// Int32Array [4, 2, 3, 4, 5]
Free Spring Boot Tutorial | Full In-depth Course | Learn Spring Boot in 10 Hours
Watch this course on YouTube at Spring Boot Tutorial | Fee 10 Hours Full Course