map() creates a new array from calling a function for every array element. map() does not execute the function for empty elements. map() does not change the original array.

Complete JavaScript Map Reference. The reference contains descriptions and examples of all Map Properties and Methods.

Complete JavaScript Map Reference. The reference contains descriptions and examples of all Map Properties and Methods.

The Map.groupBy() method groups elements of an object according to string values returned from a callback function. The Map.groupBy() method does not change the original object.

Examples. Creating a Map object by passing an array to the new Map() constructor:

Learn more about Map objects, and the difference between a Map and an Array, in the the chapter: JavaScript Maps.

Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more.

JavaScript References. W3Schools maintains a complete JavaScript reference, including all HTML and browser objects. The reference contains examples for all properties, methods and events, and is continuously updated according to the …

String, Array, TypedArray, Map and Set are all iterables, because their prototype objects have a Symbol.iterator method.

This tutorial is about the Google Maps API (Application Programming Interface). An API is a set of methods and tools that can be used for building software applications. Google Maps in HTML