expressjs/cors
Cors
This is a Node.js middleware for Express and Node.js servers that manages Cross-Origin Resource Sharing policies. It functions as a policy manager and origin validator to define which origins, HTTP methods, and headers are permitted to access server resources.
The project provides mechanisms for dynamic origin validation, allowing request origins to be checked against custom logic or databases. It also acts as an HTTP preflight request handler to process OPTIONS requests and verify server permissions before complex cross-site interactions occur.
Its capability surface covers the management of access control headers and the implementation of per-request policies. These policies can be computed on the fly based on specific request paths or runtime properties to determine access permissions.
Features
- CORS Header Management - Manages cross-origin resource sharing by manipulating Access-Control-Allow-Origin and related HTTP response headers.
- CORS Middleware - Provides middleware for Express and Node.js servers to manage Cross-Origin Resource Sharing headers and permissions.
- CORS Header Injection - Automatically appends CORS headers to responses as middleware to bypass browser same-origin policies.
- Cross-Origin Resource Sharing - Provides a comprehensive system for restricting API access to trusted domains using CORS policies.
- Cross-Origin Resource Sharing (CORS) Policies - Uses CORS headers to restrict or allow web requests from different origins.
- Cross-Origin Resource Sharing Policies - Defines which origins, HTTP methods, and headers are allowed to access server resources through CORS policies.
- Dynamic - Provides a callback mechanism to validate request origins against a database or custom logic at runtime.
- Preflight Request Interception - Detects HTTP OPTIONS requests and returns a success response early to bypass further application logic.
- CORS Pre-Flight Handling - Intercepts HTTP OPTIONS requests to validate cross-origin permissions before actual request processing.
- CORS Preflight Handlers - Automatically responds to OPTIONS requests so browsers can verify cross-origin permissions before the actual request.
- Cross-Origin Security Policies - Computes cross-origin security policies on the fly based on the properties of incoming requests.
- Scriptable Access Controls - Implements programmable logic to evaluate whether a specific incoming request origin should be granted access.
- Node.js API Security - Controls which external domains can access server resources by validating request origins and managing allowed HTTP methods.
- Request Policy Handlers - Implements middleware logic to compute and enforce unique CORS policies for each incoming request.
- Database and Backend - Middleware for enabling Cross-Origin Resource Sharing in Express.
