1. what is nodejs
a. Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine -- runtime is an environment to parse and execute source code
- browser runtime -- ES + BOM + DOM
- nodejs runtime -- ES + Sever level APIs(creat and maniplate server)
b. what nodejs can do
- create web server
- create command line tools -- npm / create-react-app / console games
2. install nodejs
3. hello world
- execute hello world
- read hello world -- buffer output to make more compatible
- write hello world
4.basic server
- create server
-request object
- send response
5.reponse to users based on requests -- only string or buffer can be responded.
