JavaScript Fetch API, HTTP requests, and real-time browser data

Network request lessons and concepts

1. Fetch API basics

   Send browser HTTP requests, read responses, handle request options, and connect network code to promises.

   Outcome: Use Fetch API calls for common browser request and response workflows.

   • JavaScript fetch
   • Fetch API
   • HTTP request JavaScript
   Study Fetch

2. FormData uploads

   Build form payloads and upload data with browser APIs that work naturally with JavaScript requests.

   Outcome: Send form fields and files with predictable request payloads.

   • FormData JavaScript
   • file upload JavaScript
   • multipart form data
   Study FormData

3. Download progress

   Track streamed response bodies and show download progress for long-running browser requests.

   Outcome: Measure network progress without blocking the page.

   • fetch progress
   • download progress JavaScript
   • ReadableStream
   Study Fetch: Download progress

4. Abort requests

   Cancel in-flight browser requests with AbortController when the user navigates or changes intent.

   Outcome: Stop stale network work and keep asynchronous UI behavior clean.

   • AbortController
   • abort fetch
   • cancel request JavaScript
   Study Fetch: Abort

5. Cross-origin requests

   Understand CORS, cross-origin request rules, and what headers allow a browser request to complete.

   Outcome: Debug browser network errors caused by origin and header policy.

   • CORS JavaScript
   • cross-origin requests
   • fetch cors
   Study Fetch: Cross-Origin Requests

6. Fetch API details

   Study Request, Response, headers, body handling, and deeper Fetch API behavior for production code.

   Outcome: Use lower-level request and response primitives deliberately.

   • Fetch API JavaScript
   • Request Response
   • HTTP headers JavaScript
   Study Fetch API

7. URL objects

   Build, parse, and update URLs safely before using them in JavaScript network requests.

   Outcome: Construct request URLs without fragile string concatenation.

   • URL object JavaScript
   • URLSearchParams
   • query parameters
   Study URL objects

8. Real-time browser communication

   Compare long polling, WebSocket, and Server-Sent Events for real-time browser updates.

   Outcome: Choose the right browser communication pattern for live data.

   • WebSocket JavaScript
   • Server-Sent Events
   • long polling
   Study WebSocket