# JavaScript Slice


This method finally clicked in my head today. So basically the way the JS Slice method works is that, it gives you back a copy of the original array. You specify where you want your copy to start. For instance, with  ```slice()``` you might as well read that as slice the original array starting from position 0. ```Slice(1)``` says, I want a slice starting from position 1, while ```slice(-1)``` says, I want a slice starting from the last item - in which case you will only get that one item. **In such cases where you don't specify the end, the slice method assumes you want a slice till the very last item**.
If you want to specify the end of your slice, you just pass it to the method, e.g. ```slice(1, 4)```, where 4 is the position you want the slice to end at. **Now the thing to note is that the item on position 4 will not be in your slice.** The slice will actually end on that number you provided minus one. So in this case you would get items starting from position 1 to position 3 of the array. So simply, when specifying the end, you just add one to it.

With this in mind, the following code is a lot easier to understand. One function uses a for loop to iterate over an array, while the other uses recursion and the slice method.
 
```
function sum(numbers){
  let total = 0
  for(let i = 0; i < numbers.length; i++){
    total += numbers[i]
 }
  return total;
 }
```
Recursion:
```
function sum(numbers){
  if(numbers.length === 1){
    //base case
    // if the array has one item, then thats the total of the array :)
    return numbers[0];
  } else{
    return numbers[0] + sum(numbers.slice(1))
  }
}
```