Incorrect Challenge Test Case result on Chrome

Challenge Name

FEDC -> Basic Javascript -> Nest one Array within Another Array https://www.freecodecamp.com/challenges/nest-one-array-within-another-array

Issue Description

var myArray = [myArray]; is treated as a correct solution. Sometimes it isn’t immediately treated as correct, but upon running tests a second time it is. I haven’t ever had to run tests more than twice to have this treated as correct.

Browser Information

• Browser Name, Google Chrome - Version 54.0.2840.59 (64-bit)
• Operating System: Linux Mint 17.3 Xfce 64-bit
• Mobile, Desktop, or Tablet: Laptop on a desk top.

I did try this bug on a Windows machine with Firefox. It isn’t present. It is present on Chrome however. I’ve used incognito mode in all cases. Windows Chrome version: 54.0.2840.71 m (64-bit)

Your Code

Full challenge code:

// Example
var ourArray = [["the universe", 42], ["everything", 101010]];

// Only change code below this line.
var myArray = [myArray]; 

[Bouncey]

You would get [undefined], because the lexer hasn’t had a chance to assign anything to myArray.

Doing the same in my console might explain it better:

let myArray = [myArray];
console.log(myArray); // Uncaught ReferenceError: myArray is not defined | this is referencing the nested myArray

If however you do:

let myArray = [];
myArray = [myArray];
console.log(myArray); // [[]]

It is not a bug with FreeCodeCamp, but a feature(?) of the language.

I hope this clears up the issue.

[zairm]

@erictleung I think you’re right, though it only takes two tries after I’ve already set myArray to something like 1 and failed the tests. I think that’s because the default line var myArray = []; actually already sets myArray to [] before the user has a chance to play with the code.

I used

// Example
var ourArray = [["the universe", 42], ["everything", 101010]];

// Only change code below this line.
var myArray = [myArray];
console.log(myArray);

to arbitrary nest myArray in the method you suggested. I did notice that each run logged myArray twice, but with 2 different values! The first was the arbitrarily nested array, while the second was always [undefined] (the keyword undefined). Firefox always returns [undefined] twice.