Tell us what’s happening:
Your code so far
function largestOfFour(arr) {
var largestNumber= [0,0,0,0];
for(var i = 0; i < arr.length; i++){
for (var sb= 0; sb < arr[i].length; sb++){
if(arr[i][sb] > largestNumber[i]){
largestNumber[i] = arr[i][sb];
}
}
}
return largestNumber;
}
largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);
Your browser information:
User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0.
Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/return-largest-numbers-in-arrays/
Why did you choose this specific array? If you were to apply your function to an array of arrays of negative numbers only, you’d be in for a surprise.
Also, you should keep in mind that this function is available.
She just used it as a placeholder, it gets modified instantly during the loop.
Note: You’ll have to calculate the sum of values in each subarray and find the largest. For example [[0, 5, 5, 0], [0, 10, 10, 5]] would mean the [0, 10, 10, 5] is the correct answer as it sums up to 25, while the first one sums up to 10.
Try to recreate these steps:
- Take each subarray and sum their values
- Place those sums in a new array
- Find the index number of the highest value in that new array
- That index number will also represent the index of a subarray with largest sum of values. That’s what you need to return.
Unless there is an array of negative numbers only, which is the case with the test her code is failing.
You might be right. I think I’ve missed something in her posts, will look into it later! 
Your logic assumes that the greatest number in the array will be larger than 0. What about an array [-75,-20,-25,-30]? One of those is the greatest number in that array but none are every going to be > largestNumber[i].
Hint: Your for loop iterates over that array. On the first iteration -75 would be the greatest number tested so far
