HTTP topic
CORS
CORS is a browser response-sharing protocol layered on HTTP. Follow the complete browser flow, then use the field references, troubleshooting paths, glossary definitions, and Lab scenario to isolate failures.
Recommended foundation
Start here
This entry establishes the shared model used by the references, diagnostics, and experiments below.
Learn
Understand the browser CORS flow
CORS is a browser response-sharing protocol layered on HTTP, not proof that the network request failed.
CORS
Reference
3 reviewed entries
intermediate
Access-Control-Allow-Origin field
Access-Control-Allow-Origin identifies which requesting origin may read a CORS response.
intermediate
Origin field
Origin identifies the source origin associated with a request without a path.
intermediate
QUERY method
QUERY asks a target resource to process enclosed query content safely and idempotently and return the result.
CORS
Troubleshoot
2 reviewed entries
CORS
Lab
3 reviewed entries
intermediate
Observe a CORS preflight
Run a simple GET and a preflighted POST, then inspect the final response shared with JavaScript.
intermediate
Observe an HTTP QUERY request
Run a safe cross-origin QUERY request and inspect the final response shared with JavaScript.
intermediate
Observe fixed response headers
Inspect how fixed response fields describe handling policy separately from response content.
CORS
Glossary
2 reviewed entries