JavaScript Function Insertion Sorting/ Function undefined

Question

I am attempting to write a javascript file that has a insertion sort function, a function to check a sorted array and return true or false, and an insertion sort function that works from the end of the array index to the beginning. Here is the code i have

function insertionSort(arr) { 
    for(var i = 1; i < arr.length; i++) { 
        var val = arr[i]; var j; for(j = i; j > 0 && arr[j-1] > val; j--) {
            arr[j] = arr[j-1]; } arr[j] = val; }
    }
function reverseInsertionSort(arr) { 
    for(var i = arr.length; i >1; i--) 
    { var val = arr[i]; var j;
        for(j = i; j > 0 && arr[j-1] > val; j--)
            { arr[j] = arr[j-1]; } arr[j] = val;
            } }
var length = Math.floor(Math.random()*100)+1;
var arr = new Array();
for(let i = 0; i < length; i++) {
  arr.push(Math.floor(Math.random()*10000)+1);
}
console.log(arr);
//function sortCheck(arr) {
//for( var i = 0 ; i < arr.length; i++){
//  if(arr[i]>rr[i+1]){
//      return false
//  }
//}
//return true}


var sortedArr = insertionSort(arr);
console.log(sortedArr);
console.log("And with reverse \n");
var reverseSortedArr = reverseInsertionSort(arr);
console.log(reverseSortedArr);
//console.log(sortCheck(sortedArr));

The issue I am having right now is that sortedArr is undefined when output with console.log, it appears that the issue is that my function is "undefined" but seeing how i define it above, i dont understand how that is.