Manipulating an Array

[Mutiplify]

Consider the following code

function frankenSplice(arr1, arr2, n) {
	let finalArray = arr2;
  finalArray.splice(n, 0, ...arr1)
	console.log(arr2)
  return finalArray;
}

frankenSplice([1, 2, 3], [4, 5, 6], 1);

console.log(arr2)

returns [4, 1, 2, 3, 5, 6]

Is finalArray just a pointer to arr2? I am a little confused about how the manipulation of arr2 is achieved.

[8-bitgaming]

You would be right that they both point to the same array. We can see this by modifying an array set to another array:

const arr1 = [1, 2, 3];
const arr2 = arr1;
arr2.push(4);
console.log(arr1);

Likewise it would follow that .splice() would modify it too:

const arr1 = [1, 2, 3];
const arr2 = arr1;
arr2.splice(2);
console.log(arr1);

We see this also when we pass an array to a function and modify it:

function foo(arr) {
  arr.push(3);
}

const arr = [1, 2];
foo(arr);
console.log(arr);