# 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... --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://hyunholee90.gitbook.io/hyho/javascript/untitled.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.