binsert

Uses binary search to insert a value into any sorted collection.

Installation

Requires Node.js 8.3.0 or above.

npm i binsert

API

The module exports a single function.

Parameters

1. Object argument:
   • Optional: compare (function, array, or any):
     • If a function: When passed two arguments a and b, expected to return -1 if a is less than b, 1 if a is greater than b, and 0 if they are equal.
     • If an array: An array of Map/object keys, the values of which can be used to compare two Maps/objects. The first key is checked first, and if the two values for that key are equal, the next key in the array is checked, and so on. If any given element is itself an array, it is interpreted as a nested keychain.
     • Otherwise: A single Map/object key.
     • If omitted: Will compare numbers and strings. Will coerce everything else into strings.
   • get (function): A callback that should return a value for a given index from 0 to length - 1.
   • Optional: insert (function): A callback that accepts the index at which value should be inserted. The callback is not expected to return anything. If insert is omitted, it is assumed you will take care of insertion later using the index return value.
   • length (positive integer): The length of the collection.
   • Optional: multiple (string): Only applies if unique is false or undefined. Specifies behavior in the event that more than one existing collection item is sort-equivalent with value. If set to first or last, then value will be inserted before/after the first/last sort-equivalent item, respectively. (This will slow down the insert operation.) Otherwise, value will be inserted anywhere in the range of sort-equivalent items.
   • Optional: set (function): A callback that accepts the index at which an existing value should be overwritten with value. This only applies if unique is true. The callback is not expected to return anything.
   • Optional: unique (bool): If set to true, then no item in the collection may be sort-equivalent with another; so if an existing item is sort-equivalent with value, it will either be overwritten with the set callback (if one is provided) or else nothing will happen (if set is not specified). If set to false, multiple sort-equivalent items are allowed, so value will always be inserted. Defaults to false.
   • value (any): The value to insert.

Return Value

Returns an object:

• found (boolean): true if compare reported that the collection already contained a value with the same sort value as value; false otherwise.
• index (positive integer): The index at which value was (or should be) inserted.

Example

const binsert = require('binsert')

const arr = ['a', 'c', 'e']
binsert({get: i => arr[i], insert: (i, v) => { arr.splice(i, 0, v) }, length: arr.length, value: 'b'}) // {found: false,  index: 1}
arr // ['a', 'b', 'c', 'e']

Related

This module is part of the “b” family of binary search modules.

• barr
• bfind