# Recursion with ES6 Spread Syntax and Destructuring.

I’ve been working with ES6 for over a year now and can easily say the spread operator and destructuring are by far my most frequently used features.

### Spread Operator

Allows the expansion of items inside an object or array - or if you’re working with functions,arguments. This is especially useful when you want to overwrite the value of a key in an object while still preserving the object’s original contents.

### Destructuring

Allows the “extraction” of particular values from an iterable list. For arrays, this extraction is index-based, while attribute values from objects are extracted using the “key” they belong to.

### Recursion using both

I coded a small recursive function that leverages both these features. It takes in a list of numbers and multiplier value, then returns the transformed list where each original value is multiplied by the mutliplier value argument.

```
function multiply(arr, multiplier, prev = []) {
// Extract the first element from the number list.
const [number, ...rest] = arr;
// Base-case: if there are no numbers to extract, then return.
if (!number) return [...prev, ...arr];
// Otherwise, we pass the remaining of the array to multiply again, the multiplier, and the accumulated transformed list.
return multiply(rest, multiplier, [...prev, number*multiplier]);
}
```