HTTP & APIs

Common request methods and the intent they usually communicate.

Term / Syntax	Name	Description	Example
GET	Read Resource	Requests a representation of a resource without intending to modify it.	GET /api/users/42
POST	Create/Process	Submits data for processing or commonly creates a new resource.	POST /api/users
PUT	Replace Resource	Commonly replaces a resource with the complete representation provided.	PUT /api/users/42
PATCH	Partial Update	Applies partial modifications to a resource.	PATCH /api/users/42
DELETE	Delete Resource	Requests removal of the target resource.	DELETE /api/users/42

Frequently encountered HTTP response status codes.

Term / Syntax	Name	Description	Example
200	OK	The request succeeded.	200 OK
201	Created	The request succeeded and created a new resource.	201 Created
204	No Content	The request succeeded and has no response body.	204 No Content
400	Bad Request	The server could not process the request because the request was invalid or malformed.	400 Bad Request
401	Unauthorized	Authentication is required or has failed.	401 Unauthorized
403	Forbidden	The server understood the request but refuses authorization.	403 Forbidden
404	Not Found	The requested resource was not found.	404 Not Found
409	Conflict	The request conflicts with the current state of the resource.	409 Conflict
500	Internal Server Error	The server encountered an unexpected error while processing the request.	500 Internal Server Error

Common metadata and data formats used in API requests and responses.

Term / Syntax	Name	Description	Example
Content-Type	Representation Type	Describes the media type of the content being sent.	Content-Type: application/json
Accept	Preferred Response Type	Tells the server which response media types the client can handle.	Accept: application/json
Authorization	Credentials	Sends credentials used to authenticate a request.	Authorization: Bearer <token>
JSON.stringify()	Serialize to JSON	Converts a JavaScript value to a JSON string.	body: JSON.stringify({ name: "Jennifer" })
response.json()	Parse JSON Response	Reads a response body as JSON and returns a Promise with the parsed data.	const data = await response.json();

Browser APIs and patterns for making asynchronous HTTP requests.

Term / Syntax	Name	Description	Example
fetch()	HTTP Request	Starts a network request and returns a Promise for a Response.	const response = await fetch("/api/users");
async	Async Function	Allows a function to use await and always returns a Promise.	async function loadUsers() { }
await	Await Promise	Waits for a Promise and returns its fulfilled value.	const response = await fetch(url);
response.ok	Success-Range Check	true when the response status is in the 200–299 range.	if (!response.ok) throw new Error(`HTTP ${response.status}`);
try...catch	Request Error Handling	Handles errors thrown while awaiting a request or processing its response.	try { await fetch(url); } catch (error) { console.error(error); }
AbortController	Cancel Request	Provides a signal that can abort fetch and other supported operations.	const controller = new AbortController(); fetch(url, { signal: controller.signal });
CORS	Cross-Origin Policy	HTTP-header mechanism controlling whether browser code can access cross-origin responses.	Access-Control-Allow-Origin: https://example.com