Got it! Thanks for the clarification.

Note: a digit can belong to two adjacent digit-pairs. For example, in string 1???9??1, 1???9 is a digit-pair, 9??1 is also a digit-pair.

Could someone explain this to me.
How does the above represent two valid digit-pairs?
Or is it a typo?

Because there are 3 ??? between the 1 and 9
However there is not three ??? which follow the 9.
So how can the answer be valid?

Also looking at the sample tests shows
Test.assertEquals(sum10("1???x9??1"), false)

That is what I would expect.

So is the description meant to read:
"***Note: a digit can belong to two adjacent digit-pairs.
For example, in string 1???9???1, 1???9 is a digit-pair, 9???1 is also a digit-pair."

Thank you

Aha! I understand now. Thank you

Thank you, akar-0

But as you can see I posted exactly the input so that you can
see what I am using!
All I did was change the 'test.assert...' string to 'console.log'
That's it!
And ran both programs which displayed the answers straightaway
As you can see

I would gladly send you the source code of my solution so that you can see what I mean, if that helps!

Greetings

I have written two different solutions which both use a loop. No recursion.
Both run fine in Visual Studio but both crash with memory problems in Codewars

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory

I have tried both 'resetting' and changing the Node versions.
I get the same errors

How do I proceed?

This is my output from Visual Code:

console.log(splitWithoutLoss("hello world!", " |"), ["hello ", "world!"]);
console.log(splitWithoutLoss("hello world!", "o|rl"), ["hello wo", "rld!"]);
console.log(splitWithoutLoss("hello world!", "ello| "), ["hello", " world!"]);
console.log(splitWithoutLoss("hello world!", "hello wo|rld!"), [
"hello wo",
"rld!",
]);
console.log(splitWithoutLoss("hello world!", "h|ello world!"), [
"h",
"ello world!",
]);

console.log(splitWithoutLoss("hello world! hello world!", " |"), [
"hello ",
"world! ",
"hello ",
"world!",
]);

console.log(splitWithoutLoss("hello world! hello world!", "o|rl"), [
"hello wo",
"rld! hello wo",
"rld!",
]);

console.log(splitWithoutLoss("hello world! hello world!", "ello| "), [
"hello",
" world! hello",
" world!",
]);

console.log(splitWithoutLoss("hello world! hello world!", "hello wo|rld!"), [
"hello wo",
"rld! hello wo",
"rld!",
]);

console.log(splitWithoutLoss("hello hello hello", " | "), [
"hello ",
" hello ",
" hello",
]);

Which Produced:

[ 'hello ', 'world!' ] [ 'hello ', 'world!' ]
[ 'hello wo', 'rld!' ] [ 'hello wo', 'rld!' ]
[ 'hello', ' world!' ] [ 'hello', ' world!' ]
[ 'hello wo', 'rld!' ] [ 'hello wo', 'rld!' ]
[ 'h', 'ello world!' ] [ 'h', 'ello world!' ]

[ 'hello ', 'world! ', 'hello ', 'world!' ] [ 'hello ', 'world! ', 'hello ', 'world!' ]

[ 'hello wo', 'rld! hello wo', 'rld!' ] [ 'hello wo', 'rld! hello wo', 'rld!' ]

[ 'hello', ' world! hello', ' world!' ] [ 'hello', ' world! hello', ' world!' ]

[ 'hello wo', 'rld! hello wo', 'rld!' ] [ 'hello wo', 'rld! hello wo', 'rld!' ]

[ 'hello ', ' hello ', ' hello' ] [ 'hello ', ' hello ', ' hello' ]

Bitwise NOTing any number x yields -(x + 1).