Slice() method question

[bananahair]

I’m working on a challenge that utilizes .slice() so I’m fooling around with it on Repl.it to get a feel for what it does. I have a question in regard to one particular response that I think I understand but I have a sneaking suspicion that I don’t understand this.

So here is the code I’m using.

for(let i = 0; i < arr.length; i++){
var oneArr = arr.slice(i);}
return arr;
}
chunkyArrayInGroups([“a”, “b”, “c”, “d”], 2);


When I console.log (oneArr) this is what I receive:

[ 'a', 'b', 'c', 'd' ] [ 'b', 'c', 'd' ] [ 'c', 'd' ] [ 'd' ]

Why is it depreciating like that?
My guess is that it is just looping through and slicing off an element each time it iterates through the sequence.

That said, when I do this:
var oneArr = arr[i].slice(i);

My console log returns a

Why? I’m perplexed by this? Is it because it stops at the first iteration?

[alhazen1]

@bananahair

for(let i = 0; i < arr.length; i++){ var oneArr = arr.slice(i);} return arr; } chunkyArrayInGroups([“a”, “b”, “c”, “d”], 2);

When I console.log (oneArr) this is what I receive:

[ 'a', 'b', 'c', 'd' ] [ 'b', 'c', 'd' ] [ 'c', 'd' ] [ 'd' ]

Why is it depreciating like that?
My guess is that it is just looping through and slicing off an element each time it iterates through the sequence.

Because that’s what slice does…

from MDN: The slice() method returns a shallow copy of a portion of an array into a new array object selected from begin to end ( end not included ). The original array will not be modified.

As you loop from 0 to 3
arr.slice(0) is [ ‘a’, ‘b’, ‘c’, ‘d’ ] (index 0 to end of array)
arr.slice(1) is [ ‘b’, ‘c’, ‘d’ ]
arr.slice(2) is [ ‘c’, ‘d’ ]
arr.slice(3) is [ ‘d’ ] (index 3 to end of array)

This is all covered in detail on MDN page for array .slice() method

Array.prototype.slice() - JavaScript | MDN

@bananahair

That said, when I do this:
var oneArr = arr[i].slice(i);

My console log returns a

Why? I’m perplexed by this? Is it because it stops at the first iteration?

String has a similar slice() method.
when i is 0 arr[i] is ‘a’, a string of one character and ‘a’.slice(0) is ‘a’ (index 0 to end of string)
when i is 1 arr[i] is ‘b’ and ‘b’.slice(1) is an empty string (index 1 to end of string)

Also covered in detail by the MDN

String.prototype.slice() - JavaScript | MDN

The MDN is a great go-to manual for anyone serious about web development. Topics are explained in great detail and have accompanying examples to demonstrate key concepts. Consider it the READ part of Read-Search-Ask

How To Get Help When You Are Stuck Coding

When you get stuck, remember: Read-Search-Ask. Read the documentation or error Search Google Ask your friends for help This is the most time-efficient way to handle being stuck, and it’s the most respectful of other people’s time, too. Most of the time, you’ll solve your problem after just one or two steps of this algorithm. And remember - you can create a new thread here on the forum with your question and you’ll often get a response quite quickly.