Intermediate Algorithm Scripting: Sum All Numbers in a Range_Help Requested

JavaScript
1

Hello. My reduce function doesn’t seem to be working. Could you tell me what I’m doing wrong? Thanks in advance!

function sumAll(arr) {
  let arrSorted = arr.sort(function(a,b) {return a - b});
  console.log(arrSorted)
  let newArr = [];
  let plusOne = 1;
  let i = 0
  newArr.push(arrSorted[0]);
  while (plusOne < arrSorted[1]) {
    newArr.push(arrSorted[0] + plusOne);
    plusOne++;
  }
  newArr.push(arrSorted[-1]);
  console.log(newArr);
  return newArr.reduce(function(a,b){
    return a + b;
  });
}

sumAll([1, 4]);
2

Sure. If you take a look at the console, your newArr for the first example ([1, 4]) is logging as [1, 2, 3, 4, undefined] – and adding undefined in your reduce function seems to be returning NaN (or a “not a number” error).

In order to debug this, I changed the last line (where you return newArr.reduce(...)), and broke it apart:

let returnValue = newArr.reduce(...);
console.log(returnValue);
return(returnValue);

This allowed me to see what you’re actually returning. In this case, you’re returning “NaN”.

3

Out of curiousity, what do you think the following line does in your code?

  newArr.push(arrSorted[-1]);
4

I thought it might return the item at index 2. I got rid of it and fixed my while loop. This seemed to work.

function sumAll(arr) {
  let arrSorted = arr.sort(function(a,b) {return a - b});
  console.log(arrSorted)
  let newArr = [];
  let plusOne = 0;
  while (arrSorted[0] + plusOne <= arrSorted[1]) {
    newArr.push(arrSorted[0] + plusOne);
    plusOne++;
  }
  console.log(newArr);
  return newArr.reduce(function(a,b){
    return a + b;
  });
}

sumAll([5, 10]);
5

little convoluted, maybe, but it looks good! well done.