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WeakMap in JavaScript - An Easy Introduction

WeakMap is one of the most underrated and least used data structures in JavaScript. There are many JavaScript developers who don’t even know they exist. This tutorial will help you understand them. You will learn about what WeakMaps are, how they work and how they differ from Maps.

A quick introduction to WeakMap

Both, Maps and WeakMaps are new data structures, or collections, introduced in [ES6]. Another example of a collection is an array. Similarly to an array, both Maps and WeakMaps allow you to store data. In case of these Maps and WeakMaps you store in the form of key-value pairs.

If you want to access some value stored in a Map, all you have to do is to use the correct key. This also works for WeakMaps. When you want to access some value stored in a WeakMap, you also have to use correct key. Both, Maps and WeakMaps allow you to add new key-value pairs and remove existing.

What if you are not sure if a Map or WeakMap contains specific key? There is a method you can use to quickly check if the key exists. So, this is where Maps and WeakMaps work in the same way. Along with these similarities, there are some important differences between these two you need to know.

Differences between Maps and WeakMaps

The first difference between Maps and WeakMaps is the type of data you can use. With Maps, you can use any data type you want to create a key for the key-value pair. This also includes objects and functions. This is not true for WeakMaps. WeakMaps allow you to create keys only with objects, not with any other data type.

This is one of the main differences between Maps and WeakMaps. Another important difference is that all keys in a WeakMap are weakly referenced. This means that objects used as key for a WeakMap can still be garbage collected. This will happen when all references to those objects are gone.

When these objects are no longer used by any part of the program garbage collection will free them from memory. It is important to note that garbage collection will not free those objects from memory immediately. These objects will be only “marked” to be garbage collected.

Only when the next “cycle” of garbage collected happens, they will actually be freed. JavaScript runs these cycles automatically. So, you don’t have to worry about it. The last big difference between Maps and WeakMaps is that WeakMaps are not iterable. You can’t iterate over them using a loop or forEach() method like you can over Maps.

This also means that you have to know the key you are looking for. Since we are talking about iterability. WeakMaps also don’t have any size property. So, you don’t really know how many pairs are inside one. Lastly, there is no clear() method that would allow to remove all data from a WeakMap.

These differences are quite important and put serious constraints on what you can do with WeakMaps. However, don’t let this discourage you from learning more about them because WeakMaps can still be useful. We will talk about this soon, but first, let’s take a look at how you can create WeakMaps and what you can do with them.

#javascript #development #language #programming #programming language #technology #theory #web #web design #web development

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WeakMap in JavaScript - An Easy Introduction

Introduction With Basic JavaScript

The world’s most misunderstood programming language is JavaScript but JavaScript is now used by an incredible number of high-profile applications. So, it’s an important skill for any web or mobile developer to enrich the deeper knowledge in it.

Unlike most programming languages, the JavaScript language has no concept of input or output. It is designed to run as a scripting language in a host environment, and it is up to the host environment to provide mechanisms for communicating with the outside world.

Its syntax is based on the Java and C languages — many structures from those languages apply to JavaScript as well. JavaScript supports object-oriented programming with object prototypes, instead of classes. JavaScript also supports functional programming — because they are objects, functions may be stored in variables and passed around like any other object.

Let’s start off by looking at the building blocks of any language: the types. JavaScript programs manipulate values, and those values all belong to a type. JavaScript’s types are:

· Number

· String

· Boolean

· Function

· Object

· Symbol

and undefined and null, which are … slightly odd. And Array, which is a special kind of object. Date and RegExp, which are objects that you get for free. And to be technically accurate, functions are just a special type of object. So the type of diagram looks like this:

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Rahul Jangid

1622207074

What is JavaScript - Stackfindover - Blog

Who invented JavaScript, how it works, as we have given information about Programming language in our previous article ( What is PHP ), but today we will talk about what is JavaScript, why JavaScript is used The Answers to all such questions and much other information about JavaScript, you are going to get here today. Hope this information will work for you.

Who invented JavaScript?

JavaScript language was invented by Brendan Eich in 1995. JavaScript is inspired by Java Programming Language. The first name of JavaScript was Mocha which was named by Marc Andreessen, Marc Andreessen is the founder of Netscape and in the same year Mocha was renamed LiveScript, and later in December 1995, it was renamed JavaScript which is still in trend.

What is JavaScript?

JavaScript is a client-side scripting language used with HTML (Hypertext Markup Language). JavaScript is an Interpreted / Oriented language called JS in programming language JavaScript code can be run on any normal web browser. To run the code of JavaScript, we have to enable JavaScript of Web Browser. But some web browsers already have JavaScript enabled.

Today almost all websites are using it as web technology, mind is that there is maximum scope in JavaScript in the coming time, so if you want to become a programmer, then you can be very beneficial to learn JavaScript.

JavaScript Hello World Program

In JavaScript, ‘document.write‘ is used to represent a string on a browser.

<script type="text/javascript">
	document.write("Hello World!");
</script>

How to comment JavaScript code?

  • For single line comment in JavaScript we have to use // (double slashes)
  • For multiple line comments we have to use / * – – * /
<script type="text/javascript">

//single line comment

/* document.write("Hello"); */

</script>

Advantages and Disadvantages of JavaScript

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Hire Dedicated JavaScript Developers -Hire JavaScript Developers

It is said that a digital resource a business has must be interactive in nature, so the website or the business app should be interactive. How do you make the app interactive? With the use of JavaScript.

Does your business need an interactive website or app?

Hire Dedicated JavaScript Developer from WebClues Infotech as the developer we offer is highly skilled and expert in what they do. Our developers are collaborative in nature and work with complete transparency with the customers.

The technology used to develop the overall app by the developers from WebClues Infotech is at par with the latest available technology.

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Niraj Kafle

1589255577

The essential JavaScript concepts that you should understand

As a JavaScript developer of any level, you need to understand its foundational concepts and some of the new ideas that help us developing code. In this article, we are going to review 16 basic concepts. So without further ado, let’s get to it.

#javascript-interview #javascript-development #javascript-fundamental #javascript #javascript-tips

WeakMap in JavaScript - An Easy Introduction

WeakMap is one of the most underrated and least used data structures in JavaScript. There are many JavaScript developers who don’t even know they exist. This tutorial will help you understand them. You will learn about what WeakMaps are, how they work and how they differ from Maps.

A quick introduction to WeakMap

Both, Maps and WeakMaps are new data structures, or collections, introduced in [ES6]. Another example of a collection is an array. Similarly to an array, both Maps and WeakMaps allow you to store data. In case of these Maps and WeakMaps you store in the form of key-value pairs.

If you want to access some value stored in a Map, all you have to do is to use the correct key. This also works for WeakMaps. When you want to access some value stored in a WeakMap, you also have to use correct key. Both, Maps and WeakMaps allow you to add new key-value pairs and remove existing.

What if you are not sure if a Map or WeakMap contains specific key? There is a method you can use to quickly check if the key exists. So, this is where Maps and WeakMaps work in the same way. Along with these similarities, there are some important differences between these two you need to know.

#javascript #weakmap