JavaScript Map

0
9K

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.

Site içinde arama yapın
Kategoriler
Read More
Business
Top 3 Mistakes in Presenting Your Product
Let's figure out what not to do to find and get your business angel. Let's list the most common...
By Dacey Rankins 2024-09-13 14:21:50 0 10K
Programming
Python List Slicing
In Python, list slicing is a common practice and it is the most used technique for programmers to...
By Jesse Thomas 2023-03-08 16:49:21 0 9K
Rehber
Inglourious Basterds. (2009)
In Nazi-occupied France during World War II, a plan to assassinate Nazi leaders by a group of...
By Leonard Pokrovski 2022-12-29 23:01:22 0 18K
Arts, Culture and Entertainment
All About Eve. (1950)
A seemingly timid but secretly ruthless ingénue insinuates herself into the lives of an...
By Leonard Pokrovski 2023-02-07 13:22:59 0 23K
Business
How Much Does It Cost to Hire a Business Consultant?
Hiring a business consultant can be a smart investment for any company looking to improve its...
By Dacey Rankins 2025-02-10 18:16:58 0 9K

BigMoney.VIP Powered by Hosting Pokrov