Copy an Array into itself in JavaScript ES6/2015

#JavaScript #ES2015 #ES6

Part of the additions to ES6 is an array method called copyWithin:

arr.copyWithin(target, start[, end = this.length])

The function takes a section of the array and copies it to another place within the array.

• target: index where to copy the elements
• start: beginning of section to copy
• end: end of section to copy. Optional, if not specified the section will go to the end of the array

Example

m

[0,1,2,3,4,5].copyWithin(4, 1, 3)
// Result: [0, 1, 2, 3, 1, 2]

Here is a visual representation of what happens:

Remarks

• As expected parameters are 0 based indexes.
• The copyWithin modifies the array itself, it does not return a copy of it.
• The array size if not modified, copyWithin only copies what fits.

#JavaScript #ES2015 #ES6