Debugger-checked code shows correct return value in console.log, so why am I returning undefined?

Question

I'm trying to determine if a passed-in array is Ascending, Descending, Rotated Ascending, or Rotated Descending. Although the now commented out console.log("RA"); near the end of the overall function shows "RA" when an appropriate string is passed into the parameters for the parent solve function, return "RA" is returning undefined . The sample array I used for the arr parameter in an invocation of solve in the console is [4,5,6,1,2,3], a Rotated Ascending array.

I've tried declaring variables and using them in place of the literal return values, and have declared them in several different locations. I have checked out and followed relevant Stack Overflow posts.

function solve(arr){

  let asc = arr.every(function (x, i) {
          return i === 0 || x >= arr[i - 1];
      });

  let desc = arr.every(function (x, i) {
          return i === 0 || x <= arr[i - 1];
      });

  if (asc){
    return "A"
  }
  if (desc){
    return "D"
  }
  if (!asc || !desc){
      arr.forEach(function(el, i){

        let rtdAsc = "RA"
        let rtdDesc = "RD"

        let ascFind = arr.find(function(el, i){
          return el >= arr[i - 1]
          })

        let descFind = arr.find(function(el, i){
          return el <= arr[i - 1];
          })

        if (ascFind && descFind){

          if (el === ascFind && arr[i] === el && arr[i+1] > ascFind){  
            return rtdAsc
              // console.log("RA")
          } else if (el === ascFind && arr[i] === el && arr[i+1] < ascFind){
            return rtdDesc
          }
        }
     })
   } 
} 
~~~~~~~~~~~

I expect the result of invoking the example `solve([4,5,6,1,2,3]);` to result in "RA" through return statements, as it does successfully through `console.log("RA");`

Answer 1

Your problem is that the part where you have console.log("RA") and return "RA" is inside the function inside arr.forEach(..) . Thus, you are correctly returning "RA" to the function inside forEach , but not returning anything to solve .

To resolve this, put a retVal before the forEach function. See below.

 function solve(arr) { let asc = arr.every(function(x, i) { return i === 0 || x >= arr[i - 1]; }); let desc = arr.every(function(x, i) { return i === 0 || x <= arr[i - 1]; }); if (asc) { return "A" } if (desc) { return "D" } let retVal = "none"; if (!asc || !desc) { arr.forEach(function(el, i) { let rtdAsc = "RA" let rtdDesc = "RD" let ascFind = arr.find(function(el, i) { return el >= arr[i - 1] }) let descFind = arr.find(function(el, i) { return el <= arr[i - 1]; }) if (ascFind && descFind) { if (el === ascFind && arr[i] === el && arr[i + 1] > ascFind) { console.log("RA"); retVal = "RA"; return; //not exactly necessary } else if (el === ascFind && arr[i] === el && arr[i + 1] < ascFind) { retVal = "RD"; return; //not exactly necessary } } }) } return retVal; } console.log(solve([4,5,6,1,2,3]));