universal-cors

CORS middleware implementation with emphasis on configurability of dynamic origins.

Install

npm i -S universal-cors

How to use

import express from 'express'
import cors, { origins } from 'universal-cors'


const app = express()

/** cors middleware to accept any pattern matching example.com subdomains */
app.use(cors({ patterns: [ /^https:\/\/.*\.example\.com/ ]}))

/** ROUTERS GO HERE */

Documentation

cors default export - middleware for auto handling preflight responses, testing dynamic origins, and attaching cors response headers when valid request occurs

cors([opts: Object]): function(req, res, next)

opts

name | type | default | description -------- | -------- | ----------- | --------------- patterns | string|RegExp|Array<string|RegExp> | required | the pattern(s) to test for cors origins, if pattern matches, the response will get valid cors response headers. preflight | function(req): responseHeaders | (req) => {} | issues preflight responses for OPTIONS method requests and returns specified headers tracing | boolean | false | toggles tracing for debugging purposes logger | Object | console | the logger object to trace to loglevel | string | 'info' | the log level to use when tracing (error, warn, info, trace)

An example of what you might set for preflight:

const preflight = req => {
  return  { 'Access-Control-Allow-Origin': req.headers.origin
          , 'Access-Control-Max-Age': 604800 // Specifies how long the preflight response can be cached in seconds
          , 'Access-Control-Allow-Methods': 'GET, PUT, POST, DELETE'
          , 'Access-Control-Allow-Headers': 'Content-Type, Authorization'
          , 'Access-Control-Allow-Credentials': true
          }
}

origins export - granular origin testing functionality

origins([opts: Object]): { isOk: function(domain: string): boolean }

opts

name | type | default | description -------- | -------- | ----------- | --------------- patterns | string|RegExp|Array<string|RegExp> | required | the pattern(s) to test for cors origins, if pattern matches, the response will get valid cors response headers. tracing | boolean | false | toggles tracing for debugging purposes logger | Object | console | the logger object to trace to loglevel | string | 'info' | the log level to use when tracing (error, warn, info, trace)