Three-Way Comparison Function (3fn)
Creates a callback that compares two objects by one or more keys.
Installation
Requires Node.js 8.3.0 or above.
npm i 3fn
API
The module exports a single function.
Parameters
- Variadic/Optional:
sortBy
(function, array, or any): A Map/object key. An array will be interpreted as a chain of nested keys. A function will be interpreted as a three-way comparison callback that accepts two arguments and returns a number. If the key is user-provided, you should wrap it in an array; otherwise you’ll have problems if the key is a function, array, or plain object. - Optional:
options
(plain object): An argument passed to the 3 and kget modules, allowing you to set their options. The most commonly-needed option isinObj
, which must be set totrue
ifsortBy
is a key which points to an inherited object property.
Return Value
A callback function that accepts a Map, Object, or other collection as its argument and returns -1
, 0
, or 1
. This callback then can be passed to the sort
function of an Array, for example.
Examples
Compare By Key
const threeFn = const personA = name: 'John'const personB = name: 'Andrew' const compare = // 1 // -1 personA personB // [personB, personA]
Compare By Inherited Key
const threeFn = const _name = Symbol'name' { this_name = name } { return this_name } const personA = 'John'const personB = 'Andrew' const compare = // 1 // -1 personA personB // [personB, personA]
Compare By Multiple Keys
const threeFn = const personA = name: 'John' age: 46const personB = name: 'John' age: 27 const compare = // Sort by name first, and by age second // 1 // -1 personA personB // [personB, personA]
Compare By Nested Keys
const threeFn = const personA = name: first: 'John'const personB = name: first: 'Andrew' const compare = // 1 // -1 personA personB // [personB, personA]
Related
This module is based on 3, the three-way comparison module.
It is also part of the fn
family of modules: