ES6 - Math.trunc()

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This function shallow copies part of an array to another location in the same array and returns it without modifying its length.

Syntax

The syntax stated below is for the array method “.copyWithin()”, where,

• target − Zero-based index at which to copy the sequence to. If negative, target will be counted from the end.

• start − This is an optional parameter. Zero-based index at which to start copying elements from. If negative, start will be counted from the end. If start is omitted, copyWithin will copy from index 0.

• end − This is an optional parameter. Zero-based index at which to end copying elements from. copyWithin copies up to but not including end. If negative, end will be counted from the end. If end is omitted, copyWithin will copy until the last index.

arr.copyWithin(target[, start[, end]])

Example

<script>
   //copy with in
   let marks = [10,20,30,40,50,60]
   console.log(marks.copyWithin(0,2,4)) //destination,source start,source end(excluding)
   console.log(marks.copyWithin(2,4))//destination,source start,(till length)
</script>

The output of the above code will be as shown below −

[30, 40, 30, 40, 50, 60]
[30, 40, 50, 60, 50, 60]