JavaScript Maps

Create Maps In JavaScript

In JavaScript, a Map holds key-value pairs here keys can be of any data type.

A map maintains the insertion order of keys and provides a size property.

Maps can be iterated directly and have built-in methods for managing key-value pairs. Maps unlike JavaScript Objects, do not have default keys.

Common Syntax Of Maps In JavaScript

Glossary:

Iterable

Object values can be looped in a “for of” loop.

Default

Define default values in none provided.

Declaration

Used to define variables, functions, and constants.

Method

Function defined within a object.

Constructor

Special method within a class used to initialize and create objects of that class.

Common Methods For Maps

Ojamboshop.com Learning JavaScript Maps

Name	Description	Example
Map()	Create a new Map.	new Map();
set()	Add elements to a Map.	set(“age”, 24);
get()	Get value of a key in a Map.	get(“age”);
Name	Description	Example

JavaScript Maps Snippet

// OjamboShop.com Learning JavaScript Maps Tutorial

// Create Map Via Passing Array
let prices = new Map([
	["Milk", 10],
	["Butter", 5],
	["Bread", 2],
]);
console.log(typeof prices);
console.log(JSON.stringify(Object.fromEntries(prices)));

// Create Map Elements Via Set
let costs = new Map();
costs.set("Juice", 3);
costs.set("Cereal", 4);
costs.set("Soap", 6);
console.log(typeof costs);
console.log(JSON.stringify(Object.fromEntries(costs)));

// Retrieve Values
console.log("Milk price: " + prices.get("Milk"));
console.log("Butter price: " + prices.get("Butter"));
console.log("Bread price: " + prices.get("Bread"));
console.log("Juice cost " + costs.get("Juice"));
console.log("Cereal cost " + costs.get("Cereal"));
console.log("Soap cost " + costs.get("Soap"));

Usage

You can use any IDE or text editor and the web browser to compile and execute JavaScript code. For this tutorial, the OjamboShop.com Learning JavaScript Course Web IDE can used to input and compile JavaScript code for the Maps.

Open Source

JavaScript follows the ECMAScript standard and is licensed under the W3C Software License by web browser vendors and runtime environment vendors. This allows commercial use, modification, distribution, and allows making derivatives proprietary.

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Conclusion:

JavaScript makes it easy to use create Maps. Maps are iterable and used to store key-value pairs of any data type where the keys maintain their insertion order.

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References:

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• Learning PHP Course on OjamboShop.com
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• Learning Python Ebook on Amazon
• Learning PHP Ebook on Amazon
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