AJAX를 구성하는 기반기술

웹 페이지 표현을 위한 HTML, CSS
데이터에 접근하거나, 화면 구성을 동적으로 조작하는 DOM
데이터 교환에 사용되는 JSON이나 XML
웹 서버와 비동기적 통신을 위한 XMLHttpRequest 객체
JavaScript
GET은 데이터를 받아오기 위한 요청입니다.
POST는 데이터를 전송(삽입)하기 위한 요청입니다.
CORS (Cross-Origin Resource Sharing)
XSS, CSRF
Cross-Origin Resource Sharing(CORS) is a mechanism that uses additional HTTP headers to tell a browser to let a web application running at one origin (domain) have permission to access selected resources from a server at a different origin. A web application executes a cross-origin HTTP request when it requests a resource that has a different origin (domain, protocol, and port) than its own origin.
처음 전송되는 리소스의 도메인과 다른 도메인으로부터 리소스가 요청될 경우 해당 리소스는 cross-origin HTTP 요청에 의해 요청됩니다.
For security reasons, browsers restrict cross-origin HTTP requests initiated from within scripts. For example, XMLHttpRequest and Fetch API follow the same-origin policy. This means that a web application using those APIs can only request HTTP resources from the same origin the application was loaded from, unless the response from the other origin includes the right CORS headers.
idempotent: 멱등의
Rest is a contract for how clients can interact with URLs. Each HTTP verb has a specific meaning.
http status codes
1xx: hold on, 2xx: here you go, 3xx: go away, 4xx: you screwed up, 5xx: I screwed up