Search javascript array from the *right* to find the (index of the) *last* element satisfying a condition

findLastIndex.js

// Returns the index of the last array element that satisfies a condition function. Otherwise, returns -1
// Similar to Array.prototype.findIndex, but finds the *last* element by searching from the right
// Parameters are exactly the same as findIndex:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex
function findLastIndex(array, callbackFn, thisArg) {
  for (let i = array.length - 1; i >= 0; i--) {
    if(callbackFn.call(thisArg, array[i], i, array)) {
      return i
    }
  }
  
  return -1
}

nums = [3,1,4,1,5]
console.log(findLastIndex(nums, e => e === 4))
console.log(findLastIndex(nums, e => e === 1))
console.log(findLastIndex(nums, e => e === 7))