JavaScript | Array copyWithin()

The copyWithin() method copies part of an array to the same array and returns it, without modifying its size i.e, copies array element of a array within the same array.

Syntax:

array.copyWithin(target, start, end)

Parameters:
target : The index position to copy the elements to(Required).
start : It is optional. The index position to 
start copying elements from  (default is 0).
end : It is optional. The index position to 
stop copying elements from (default is array.length).
Return value:
It returns the modified array.

JavaScript Version : ECMAScript 6
Browser Support:



Chrome   45.0
Edge     12.0
Firefox     32.0
Opera     32.0
IE       No

Examples

Program 1:

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// Input array
var array = [ 1, 2, 3, 4, 5, 6, 7 ];
  
// placing at index position 0 the element 
// between index 3 and 6
console.log(array.copyWithin(0, 3, 6));

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Output:

Array [4, 5, 6, 4, 5, 6, 7]

Program 2:



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// Input array
var array = [ 1, 2, 3, 4, 5, 6, 7 ];
  
// placing from index position 0 the 
// element from index 4
console.log(array.copyWithin(0, 4));

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Output:

Array [5, 6, 7, 4, 5, 6, 7]

Program 3:

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// Input array
var array = [ 1, 2, 3, 4, 5, 6, 7 ];
  
// placing from index position 3 
// the element from index 0
console.log(array.copyWithin(3));

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Output:

Array [1, 2, 3, 1, 2, 3, 4]

Application: Whenever we need to copy the content of any array to the same array that time we use array.copyWithin() element in javaScript.

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// Input array
var array = [ 1, 2, 3, 4, 5, 6, 7 ];
  
// placing at index position 0 the
// element between index 4 and 5
console.log(array.copyWithin(0, 4, 5));

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Output:

Array [5, 2, 3, 4, 5, 6, 7]


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