Very explanatory and clear arguments. Thank you to make me understand it. Cheers :)

It's an initial value for the accumulator argument.

Let's say the function your calling in reduce on an array is as follows:

myfunc = function (accumulator, value) { return accumulator + value };

Then without providing a initial value for the accumulator

[1, 2].reduce(myFunc)

would be equivalent to the following:

myfunc(1,2); // results in 3

Though let's ay we provide an initial value for the accumulator as 3

[1, 2].reduce(myFunc, 3)

then that would be the equvalent of:

myfunc(myfunc(3, 1), 2) // results in 6

Or at least that's how I understand it.

In this case the first value of the array is an array and we want our accumulator to be a number so want to provide that 0.

But yea, you can go further,

[1,2,3].reduce(myfunc, 4);
// equivalent to
myfunc(myfunc(myfunc(4,1), 2), 3);

It's also functionally equivalent to not providing the initial accumulator value and instead prepending it to the array.

[1,2,3].reduce(myfunc, 4);
// equivalent to
[4,1,2,3].reduce(myfunc);

zero is a default value, you could set it to something else

I learned something new about the use of reduce. But I cant understand what does the comma (,) and the zero do at the end. Could someone explain me please?

Suggesting to add random tests to the Rust version

'Looks like you've solved it'

'Looks like you've solved it'

'Looks like you've solved it'

Thank you. I had not seen String.prototype.someFunction before and I was confused about how to access the input string :)

Hi Mate

Hello

I tried itnonce , and it worked. Although ,I was impressed with the works by others.
The thing make sense

I also forgot about destructuring as well. However, it does work without destructuring. I think you forgot to initialize your accumulator. You need to add the ,0 after the function to initialize the accumulator. Hope that helps!