CODEWITHSUNDEEP
javascriptreactjsfunctional-programmingreduximmutable.js
AndrewMcLagan
AndrewMcLagan

Reputation: 13987

Immutable JS - Creating an OrderedMap from a List

I have a List

const results = [94, 88, 121, 17];

and also a Map

const posts = {
   94: { title: 'Foo bar', content: 'Blah blah blah...' },
   88: { title: 'Bar Foo', content: 'Blah blah blah...' },
   121: { title: 'Bing bang', content: 'Blah blah blah...' },
   17: { title: 'Ning nang', content: 'Blah blah blah...' },
};

The List actually holds the order of the items in the Map as maps/objects can not guarantee order.

Whats the most efficient way to create an OrderedMap using both the List and the Map above?

Upvotes: 3

Views: 2713

Answers (2)

Akshay Vijay Jain
Akshay Vijay Jain

Reputation: 15935

Javascript Map https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map now remembers the insertion order. so you can use the Javascript Map.

// you can either create Map from existing object
const myMap = new Map(Object.entries(posts));

// or you can insert one by one, 
myMap.set(94,{ title: 'Foo bar', content: 'Blah blah blah...' })

// NOTE: key in map need not be string only

// map can be iterated using forEach
myMap.forEach((value, key) => {
  console.log(`${key} = ${value}`);
});

Upvotes: 0

Ethan Brown
Ethan Brown

Reputation: 27282

There's no built-in constructor in Immutable.js that will handle this, so you'll have to do the mapping yourself:

const orderedPosts = new OrderedMap(results.map(key => [key, posts[key]]))

Upvotes: 3

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