Last insertion index in sorted array
JavaScript, Array · Oct 22, 2020
Finds the highest index at which a value should be inserted into an array in order to maintain its sort order.
- Loosely check if the array is sorted in descending order.
- Use
Array.prototype.reverse()andArray.prototype.findIndex()to find the appropriate last index where the element should be inserted.
const sortedLastIndex = (arr, n) => {
const isDescending = arr[0] > arr[arr.length - 1];
const index = arr
.reverse()
.findIndex(el => (isDescending ? n <= el : n >= el));
return index === -1 ? 0 : arr.length - index;
};sortedLastIndex([10, 20, 30, 30, 40], 30); // 4
