orderedmap

What is orderedmap?

The orderedmap npm package provides a data structure that maintains the order of keys as they are added. This is useful for scenarios where the order of elements is important, such as in configuration files, ordered collections, or when you need predictable iteration order.

What are orderedmap's main functionalities?

Creating an OrderedMap

This feature allows you to create a new instance of an OrderedMap. The OrderedMap will maintain the order of keys as they are added.

const OrderedMap = require('orderedmap');
const map = new OrderedMap();

Adding and Retrieving Elements

You can add elements to the OrderedMap using the set method and retrieve them using the get method. The order of keys is preserved.

map.set('key1', 'value1');
map.set('key2', 'value2');
console.log(map.get('key1')); // Outputs: 'value1'

Iterating Over Elements

This feature allows you to iterate over the elements in the OrderedMap in the order they were added. This is useful for scenarios where the order of elements is important.

map.set('key1', 'value1');
map.set('key2', 'value2');
for (let [key, value] of map) {
  console.log(key, value);
}

Deleting Elements

You can delete elements from the OrderedMap using the delete method. This will remove the element and maintain the order of the remaining elements.

map.set('key1', 'value1');
map.delete('key1');
console.log(map.has('key1')); // Outputs: false

Other packages similar to orderedmap

immutable

The immutable package provides a variety of immutable data structures, including OrderedMap. It offers more features and guarantees immutability, which can be beneficial for functional programming and state management in applications like React.

es6-map

The es6-map package is a polyfill for the ES6 Map, which maintains the order of keys as they are added. While it is not specifically designed for ordered maps, it provides similar functionality and is a standard part of modern JavaScript.

README

OrderedMap

Persistent data structure representing an ordered mapping from strings to values, with some convenient update methods.

This is not an efficient data structure for large maps, just a minimal helper for cleanly creating and managing small maps in a way that makes their key order explicit and easy to think about.

License: MIT

Reference

The exported value from this module is the class OrderedMap, instances of which represent a mapping from strings to arbitrary values.

OrderedMap.from(value: ?Object | OrderedMap) → OrderedMap
Return a map with the given content. If null, create an empty map. If given an ordered map, return that map itself. If given an object, create a map from the object's properties.

Methods

Instances of OrderedMap have the following methods and properties:

get(key: string) → ?any
Retrieve the value stored under key, or return undefined when no such key exists.

update(key: string, value: any, newKey: ?string) → OrderedMap
Create a new map by replacing the value of key with a new value, or adding a binding to the end of the map. If newKey is given, the key of the binding will be replaced with that key.

remove(key: string) → OrderedMap
Return a map with the given key removed, if it existed.

addToStart(key: string, value: any) → OrderedMap
Add a new key to the start of the map.

addToEnd(key: string, value: any) → OrderedMap
Add a new key to the end of the map.

addBefore(place: string, key: value: string, value: any) → OrderedMap
Add a key after the given key. If place is not found, the new key is added to the end.

forEach(f: (key: string, value: any))
Call the given function for each key/value pair in the map, in order.

prepend(map: Object | OrderedMap) → OrderedMap
Create a new map by prepending the keys in this map that don't appear in map before the keys in map.

append(map: Object | OrderedMap) → OrderedMap
Create a new map by appending the keys in this map that don't appear in map after the keys in map.

subtract(map: Object | OrderedMap) → OrderedMap
Create a map containing all the keys in this map that don't appear in map.

size: number
The amount of keys in this map.