sortedIndexOf (Lodash compatibility)

Implement binary search directly

This sortedIndexOf function operates slowly due to complex binary search handling and type validation.

Instead, implement faster, more modern binary search directly or use Array.prototype.indexOf().

Finds the index where a value first appears in a sorted array.

const index = sortedIndexOf(array, value);

Reference

sortedIndexOf(array, value)

Use sortedIndexOf to find the index where a specific value first appears in a sorted array. It uses binary search to find the value quickly.

import { sortedIndexOf } from 'es-toolkit/compat';

// Find value in number array
sortedIndexOf([11, 22, 33, 44, 55], 33);
// Returns 2

// When value doesn't exist
sortedIndexOf([11, 22, 33, 44, 55], 30);
// Returns -1

// When duplicate values exist, returns the first index
sortedIndexOf([1, 2, 2, 3, 3, 3, 4], 3);
// Returns 3 (position of the first 3)

// 0 and -0 are treated as equal
sortedIndexOf([-0, 0], 0);
// Returns 0

Empty arrays, null, or undefined return -1.

import { sortedIndexOf } from 'es-toolkit/compat';

sortedIndexOf([], 1); // -1
sortedIndexOf(null, 1); // -1
sortedIndexOf(undefined, 1); // -1

Parameters

• array (ArrayLike<T> | null | undefined): The sorted array. Using an unsorted array can produce incorrect results.
• value (T): The value to find.

Returns

(number): Returns the index where the value first appears. If the value doesn't exist, returns -1.