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목표

1. Node.js 한 문장으로?
2. Javascript, V8, Server-side, Runtime 뭐지?
3. Node.js 장점은?
4. Package manager 사용해서 Node.js 설치
5. REPL과 .js 사용해서 javascript 코드를 node.js에서 실행
6. Node.js 모듈 시스템? Custom 모듈 만들기
7. file system 모듈 사용, 동기/비동기 개념 파악

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Node.js is a Server Side, open source, javascript runtime in Chrome browser using the V8 Javascript engine.

V8 Javascript engine computes Javascript code into simpler byte code.

Runtime is a stage of the programming lifecycle. Time that a program is running alongside all the external instructions needed for proper execution.

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why use it?

1. Front and back-end use same language = reuse by modules

2. Javascript-based = easy entry into server-side programming

3. SUPER FAST: JIT(Just-in-time) compilation
   interpreter = translate program 1 statement at a time
   compiler = scans entire program into machine code

4. Asynchronous I/O
   multiple input/outputs at a time
   

5. Micro Service Architecture (MSA) compatibility
   

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REPL

Read Eval Print Loop
대화형 Shell: fast test without creating file

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Running Node.js

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Module

Modulation:

process by which data/info is converted into electrical/digital signal for transfer

1. Global variables and Local variables be independent
2. EXPORTS to make public (open source?)

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Module 만들고 사용