I need a function which searches through an array and returns the last set of numbers after the last string?

Question

I need a function called getLastNumbers which searches through an array and returns the last set of numbers after the last operator.

for example:

[1, 1, 1, 1, 1, 1, "+", 2, 2, 2, 2, 2, 2, "*", 3, 3, 3, 3, 3, "-", 6, 6, 6, 6] Returns 6666

[1, 1, 1, 1, "+", 6, 6, 6, 6, 6, 6, "*", 9, 9, 9, 9, 9, "-", 6, 6, 6, 6, "+", 3, 3, 3] Returns 333

[7, "*", 7, "-", 6, "+", 3, "+", 6, "+", 3, 3, 3, 3, 3, "+", 6, "-", 5, 5, 5, 5, 5, 5, "*", 9, 9] Returns 99

[5, "*", 5] returns 5

To clarify, I will never know how many numbers or operators the user may input.

See my long winded attempt below attempt below:

function getLastNumber(arr) {
  let number = arr.filter(i => i === '*' || i === '/' || i === '+' || i === '-').length;

  let counter = 0;
  let arrayLength = arr.length;
  let lastOpIndex = [];

  for (let i = 0; i < arr.length; i++) {
    if (arr[i] === '*' || arr[i] === '+' || arr[i] === '-' || arr[i] === '/') {
      counter++;
      if (counter === number) {
        lastOpIndex.push(arr.indexOf(arr[i]));
      }
    }
  }

  let lastOpNum = parseInt(lastOpIndex.toString());
  let startNum = lastOpNum + 1;
  let mathNum = (arrayLength - lastOpNum) - 1;


  let finalArray = [];

  for (let i = startNum; i < arr.length; i++) {
    finalArray.push(arr[i]);
  }

  let strResult = finalArray.toString().split(',').join('');

  let finalResult = parseInt(strResult);

  return finalResult;
}

getLastNumber([1, "+", 3, 3, 3, 3, 3, "+", 6, "+", 9, "*", 6, 6, 6, 3, 6, 6, 6, "-", 5, "*", 9, 9, 9, 9, 9, 9, 9, '/', 6, 8, 9, 9, '*', 8, 8, 8, 7]);

Answer 1

 function filterNumbers(arr){
            let a = arr.lastIndexOf("*"); // find last index of *
            let b = arr.lastIndexOf("+"); // find last index of +
            let c = arr.lastIndexOf("-"); // find last index of -
            let d = arr.lastIndexOf("/"); // find last index of /
            let ind = Math.max(a, b, c, d); //find the max index
            console.log(ind);
            let newarr = arr.splice(ind+1,arr.length); //splice array 
            console.log(newarr);
         return newarr;
        }
     filterNumbers([1, 1, 1, 1, 1, 1, "+", 2, 2, 2, 2, 2, 2, "*", 3, 3, 3, 3, 3, 6, 6, 6, 6,1]);
          filterNumbers([1, 1, 1, 1, 1, 1, "+", 2, 2, 2, 2, 2, 2, "*", 3, 3, 3, 3,"/", 3, 6, 6, 6, 6,1]);

Answer 2

As the question is open again i will extend on my comment. I think they way you're trying to achieve this is a bit to complicated.

Here is my approach just turning the problem arround and starting with the last index instead of the first one. As soon as I find an operator I just break the loop and return the saved values in reversed order.

function getLastNumber(arr){
 let ret = [];
 for(let i = arr.length - 1; i >= 0 ; i--) {
   if(arr[i] !== '*' && arr[i] !== '+' && arr[i] !== '-' && arr[i] !== '/') {
       ret.push(arr[i]);
   } else {
       break;
   }
 }
 return ret.reverse().toString();
}
console.log(getLastNumber([1, "+", 3, 3, 3, 3, 3, "+", 6, "+", 9, "*", 6, 6, 6, 3, 6, 6, 6, "-", 5, "*", 9, 9, 9, 9, 9, 9, 9, '/', 6, 8, 9, 9, '*', 8, 8, 8, 7]));
console.log(getLastNumber([1, 1, 1, 1, "+", 6, 6, 6, 6, 6, 6, "*", 9, 9, 9, 9, 9, "-", 6, 6, 6, 6, "+", 3, 3, 3]));
console.log(getLastNumber([7, "*", 7, "-", 6, "+", 3, "+", 6, "+", 3, 3, 3, 3, 3, "+", 6, "-", 5, 5, 5, 5, 5, 5, "*", 9, 9]));
console.log(getLastNumber([5, "*", 5]))