> For the complete documentation index, see [llms.txt](https://hyunholee90.gitbook.io/hyho/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hyunholee90.gitbook.io/hyho/javascript/untitled.md).

# Javascript is...

## JavaScript is...

JavaScript is the Programming Language for the Web. Also can update and change both HTML and CSS with calculate, manipulate and validate data. JavaScript is a prototype type object-oriented language. Thus, class-free object-oriented programming style can implement chain, capsulizing, closure.

### 1. JavaScript Execution Environment

All browsers and Node.js have a built-in JavaScript engine. Therefore, both environments can run JavaScript. But the browser and Node.js have different purposes.

The browser provides a Web API (Document Object Model) specific to the client-side environment. The primary goal is to render the web page on the screen by running HTML, CSS, and JavaScript.

* Support ECMAScript, DOM, BOM, XMLHttpRequest, Fetch, requestAnimationFrame, SVG, Web  Storage, Web Component, Web worker.

Node.js is not a language, Node.js feature is provided for the server side environment. Also, It does not provide a Web API (DOM API). Node.js also provides a built-in File system that allows to create and modify files.

* Support ECMASscript, Node.js only.

### 2. Programming Language

There are compiler and interpreter methods for passing commands to a computer. This serves as a translator that translates the human-understandable syntax into machine-language.

### 3. JavaScript Feature

Immediately execute the source code as an interpreter language. Javascript is a multi-paradigm programming language that supports imperative, functional, prototype-based object-oriented programming.

### 4. ECMAScript is...