JavaScript Map

0
8K

Map objects are collections of key-value pairs. A key in the Map may only occur once; it is unique in the Map's collection. A Map object is iterated by key-value pairs — a for...of loop returns a 2-member array of [key, value] for each iteration. Iteration happens in insertion order, which corresponds to the order in which each key-value pair was first inserted into the map by the set() method (that is, there wasn't a key with the same value already in the map when set() was called).

The specification requires maps to be implemented "that, on average, provide access times that are sublinear on the number of elements in the collection". Therefore, it could be represented internally as a hash table (with O(1) lookup), a search tree (with O(log(N)) lookup), or any other data structure, as long as the complexity is better than O(N).

Key equality

Value equality is based on the SameValueZero algorithm. (It used to use SameValue, which treated 0 and -0 as different. Check browser compatibility.) This means NaN is considered the same as NaN (even though NaN !== NaN) and all other values are considered equal according to the semantics of the === operator.

Search
Categories
Read More
Death
The Unspoken Guest: Death's Role in Society
In every society, death is an inevitable part of the human experience, yet it remains one of the...
By Dacey Rankins 2024-06-06 17:08:45 0 13K
Financial Services
Market equilibrium
Key points Supply and demand curves intersect at the equilibrium price. This is the...
By Mark Lorenzo 2023-02-10 14:23:05 0 10K
Artificial Life
Artificial Life
Artificial life (a-life, from artificial life) is the study of life , living...
By Michael Pokrovski 2024-03-20 19:30:41 0 22K
Organizations
The Backbone of Sports Excellence: A Look into Sports Organizations
The Backbone of Sports Excellence: A Look into Sports Organizations Sports organizations serve...
By Leonard Pokrovski 2024-07-03 00:17:55 0 19K
Business
How to Write a Business Plan for a Small Business: A Step-by-Step Guide
Writing a business plan is an essential step for any small business owner looking to formalize...
By Dacey Rankins 2024-12-23 15:59:47 0 6K
image/svg+xml


BigMoney.VIP Powered by Hosting Pokrov