JavaScript: Get the highest index at which value should be inserted into array in order to maintain its sort order
JavaScript fundamental (ES6 Syntax): Exercise-141 with Solution
Highest Index for Sorted Insertion
Write a JavaScript program to get the highest index at which 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() and Array.prototype.findIndex() to find the appropriate last index where the element should be inserted.
Sample Solution:
JavaScript Code:
//#Source https://bit.ly/2neWfJ2
// Define the 'sortedLastIndex' function
const sortedLastIndex = (arr, n) => {
// Determine if the array is sorted in descending order
const isDescending = arr[0] > arr[arr.length - 1];
// Find the index where 'n' should be inserted into the sorted array
const index = arr
.reverse() // Reverse the array to search from the end
.findIndex(el => (isDescending ? n <= el : n >= el)); // Find the index based on sorting order
// Return the index after adjusting for the reversed array and considering array length
return index === -1 ? 0 : arr.length - index;
};
// Test the 'sortedLastIndex' function
console.log(sortedLastIndex([10, 20, 30, 30, 40], 30)); // Output: 4
Output:
4
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-141-1 by w3resource (@w3resource) on CodePen.
For more Practice: Solve these Related Problems:
- Write a JavaScript program that finds the highest index for inserting a value into a sorted array while maintaining order.
- Write a JavaScript function that scans a sorted array to determine the last position where a new value can be inserted.
- Write a JavaScript program that implements a binary search variant to locate the highest index for sorted insertion.
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