Understanding maps in JavaScript

A brief intro to the JavaScript map object and the methods and properties we can use to work with it.

This article looks to explain what a map is and to go through some of the various methods and properties available when working with maps.

What is a map?

A map is a collection of key:value pairs that can use any type of data as a key and maintain the order of its entries.

This creates an empty map:

We can also initialise a map with values by passing in an array of arrays.

Adding properties to a map

Looking at the map in the console we see the new values and properties:

This looks similar to an object using string-based keys, but with a map we can use any type of data as a key.

Maps do not allow for the duplicate use of key values. In the following example the string one and the number one get treated as unique keys, but…

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