Understanding JavaScript Engines as a Web Developer
Tags: javascript, webdev, programming, beginners
Published: 2022-06-26 22:34:00

An engine is a software component that interprets and executes code. When it comes to programming languages, there are specific types of engines that are responsible for the execution process. This article covers everything you need to know about JavaScript engines as a web developer. You will learn about the different JavaScript engines and their roles as well as when and where you can use them. Keep reading to discover more!

## What is a JavaScript Engine?
Simply put, a JavaScript engine is a piece of software that interprets the code written in JavaScript programming language and executes those instructions on a computer system. A JavaScript engine is the heart of a browser. It’s responsible for running JavaScript code seamlessly. The code you write in a JavaScript file gets parsed, then interpreted, and finally executed. In addition to running JavaScript code, JavaScript engines also provide the functionality to create and manipulate HTML elements. They also support functions such as CSS and other web standards.

## Types of JavaScript Engines
 
### Client-side JavaScript Engines 
The client-side JavaScript engine is responsible for the execution, parsing, and compilation of the JavaScript code that runs in the web browser. The client-side JavaScript engine is also responsible for the execution of the code that runs when a user requests the server. This is code that is executed on the client-side but does not create or change any user interface elements. 

### Server-side JavaScript Engines
 
Server-side JavaScript engines are responsible for the execution of the JavaScript code on the server. This code is executed before the server sends the response back to the user. The code runs on the server to generate HTML that is then sent to the user. 

### Hybrid JavaScript Engines
 A hybrid engine is a combination of client-side and server-side engines. In most cases, hybrid engines use a language that compiles to both JavaScript and another language such as Java or C#.

## How to find out which engine your browser uses?
To find out which engine your browser uses, you can use the following function: console.log(navigator.userAgent); You can also use a tool like WhatEngine to find out which engine your browser is using.

## Why are JavaScript Engines important for web developers?
JavaScript engines are important for web developers because they make the development process much easier and faster. The job of a JavaScript engine is to execute the code written in JavaScript. JavaScript engines can work either on the browser or on the server. The most important thing is that they produce the same result. Modern JavaScript engines are fast and can handle large amounts of code because of their parallelism.

## V8
A high-performance, open-source, JavaScript engine by Google
Google created its open-source JavaScript engine called V8 which is used in the Chrome web browser. V8 is the main JavaScript engine that runs in the Chrome browser. This JavaScript engine is written in C++. V8 is one of the most popular JavaScript engines used by developers. It is used in more than just Chrome. Other browsers like Safari, Opera, and Firefox use V8 as well. V8 is a high-performance JavaScript engine. It can execute 2 billion JavaScript instructions per second on a user’s computer. V8 is one of the most feature-rich JavaScript engines available. It has a rich set of APIs, a built-in debugger, and a runtime environment.

## SpiderMonkey
An open source interpreter by Mozilla
SpiderMonkey is an open-source interpreter written by Mozilla. It is used as the default JavaScript engine in Firefox. It is also used in other products like Firefox Developer Tools and the Rust code editor. SpiderMonkey is designed to execute JavaScript code quickly. It can execute approximately one million JavaScript instructions per second on a user’s computer.

## Conclusion
JavaScript engines are crucial for the functionality of the web. Modern browsers use highly optimized JavaScript engines that can execute millions of instructions per second. These engines make it possible for web developers to create complex applications that run in the browser. JavaScript engines are responsible for executing the code written in JavaScript. They can also execute code that does not create or change any user interface element. JavaScript engines are important for web developers because they make the development process easier and faster.