What is Javascript?
Javascript is a programming language that enables you to create dynamically updating content, control multimedia etc.
JavaScript engine
It is a software component that executes js code.
earlier js engines were interpreters but all relevant modern engines use JUST-IN-TIME compilation for improved performance.
Developed by web browser vendors, every major browser has one JS engine.
Js engine work in concert with the rendering engine via the DOM
What is a Rendering Engine?
Rendering engine or browser engine or layout engine: core software component of every major web browser.
The browser engine's primary job is to transform HTML documents and other resources of a web page into an interactive visual representation on a user's device.
the browser has an embedded engine that they use sometimes known as a “Javascript virtual machine”.
example:
chrome, opera, Edge use the V8 engine firefox
use- spider monkey.
How does an engine work?
engines read the script
it converts that script into machine code
then machine code run, pretty fast
what makes js unique?
full integration with HTML and css
simple things are done simply
supported by all major browsers and enabled by default.