JavaScript Sorting Algorithm: Sorted IndexBy

JavaScript Sorting Algorithm: Exercise-20 with Solution

Find Lowest Insert Index

Write a JavaScript program to find the lowest index at which a value should be inserted into an array to maintain its sorting order. This is based on the provided iterator function.

• Loosely check if the array is sorted in descending order.
• Use Array.prototype.findIndex() to find the appropriate index where the element should be inserted, based on the iterator function fn.

Sample Solution:

JavaScript Code:

const sortedIndexBy = (arr, n, fn) => {
  const isDescending = fn(arr[0]) > fn(arr[arr.length - 1]);
  const val = fn(n);
  const index = arr.findIndex(el =>
    isDescending ? val >= fn(el) : val <= fn(el)
  );
  return index === -1 ? arr.length : index;
};

console.log(sortedIndexBy([{ x: 4 }, { x: 5 }], { x: 4 }, o => o.x));

Sample Output:

0

Flowchart:

Live Demo:

See the Pen javascript-common-editor by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that finds the lowest index at which a given value should be inserted into a sorted array using binary search.
• Write a JavaScript function that handles duplicate values by returning the first possible insertion point.
• Write a JavaScript function that iterates through an array to determine the correct insertion index and returns it.
• Write a JavaScript function that validates the input and simulates insertion to verify the computed lowest index.

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