Splice() and spread operator (...)

[karlito]

Hello,
Is it possible to use spread operator (…) with splice() ?
Exemple:
If I want add an arr1 in other arr2 from his index “n”:

let result = arr2.splice(n, 0, ...arr1);

Is it possible or not ?

[JeremyLT]

Seems like it might be possible. What happens if you try it?

Array.prototype.splice() - JavaScript | MDN

[karlito]

They don’t talk about … (spread).
furthermore they give as example only arrays with strings inside.

But that’s works now.
This my solution:

function frankenSplice(arr1, arr2, n) {
  let copyArr2 = arr2.slice(0);
  copyArr2.splice(n, 0, ...arr1);
  return copyArr2;
}

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

I made the same mistake like in this other topic.
https://forum.freecodecamp.org/t/title-case-a-sentence-cascading-methodes/476760/3
I’m still really not well understand with that.

If I write this code, that not works but why ?

function frankenSplice(arr1, arr2, n) {
  let copyArr2 = arr2.slice(0);
  let result = copyArr2.splice(n, 0, ...arr1);
  return result;
}

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

[karlito]

Hiiii actually I think I just understood

[JeremyLT]

@karlito

furthermore they give as example only arrays with strings inside.

An array is an array. There is nothing special about arrays of strings vs arrays of numbers.

Spread syntax (...) - JavaScript | MDN

Spread syntax ( ... ) allows an iterable such as an array expression or string to be expanded in places where zero or more arguments (for function calls) … are expected

So I would expect spread to work fine in turning an array into a number of optional arguments for the splice() function call.