Count the number of times a value appears in a JavaScript array

Count duplicate| Solution |JavaScript.js

let arr = [3, 2, 1, 3];
function countDuplicate(arr) {
  let number = 0;
  arr.find((item, index) => {
    if (arr.indexOf(item) !== index) {
     number=item // find the duplicate (return 3)
    }
  });
  // you can use just the function below if you know the exact value for the duplicate
    function getOccurrence(array, value) {
      let count = 0;
      array.forEach((v) => (v === value && count++));// get how many times as the duplicate appeared
      return count; //(return 2 because 3 appeared 2 times)
  }
  return (getOccurrence(arr,number))
}
console.log(countDuplicate(arr)) // console.log 2 becuase