fastify-cors

fastify-cors enables the use of CORS in a Fastify application.

Supports Fastify versions >=2.x Please refer to this branch and related versions for Fastify ^1.x compatibility.

Install

npm i fastify-cors

Usage

Require fastify-cors and register it as any other plugin, it will add a preHandler hook and a wildcard options route.

const fastify = require('fastify')()

fastify.register(require('fastify-cors'), { 
  // put your options here
})

fastify.get('/', (req, reply) => {
  reply.send({ hello: 'world' })
})

fastify.listen(3000)

You can use it as is without passing any option, or you can configure it as explained below.

Options

origin: Configures the Access-Control-Allow-Origin CORS header. The value of origin could be of different types:
- Boolean - set origin to true to reflect the request origin, or set it to false to disable CORS.
- String - set origin to a specific origin. For example if you set it to "http://example.com" only requests from "http://example.com" will be allowed.
- RegExp - set origin to a regular expression pattern which will be used to test the request origin. If it's a match, the request origin will be reflected. For example the pattern /example\.com$/ will reflect any request that is coming from an origin ending with "example.com".
- Array - set origin to an array of valid origins. Each origin can be a String or a RegExp. For example ["http://example1.com", /\.example2\.com$/] will accept any request from "http://example1.com" or from a subdomain of "example2.com".
- Function - set origin to a function implementing some custom logic. The function takes the request origin as the first parameter and a callback as a second (which expects the signature err [object], allow [bool]), async-await and promises are supported as well. Fastify instance is bound to function call and you may access via this.
methods: Configures the Access-Control-Allow-Methods CORS header. Expects a comma-delimited string (ex: 'GET,PUT,POST') or an array (ex: ['GET', 'PUT', 'POST']).
allowedHeaders: Configures the Access-Control-Allow-Headers CORS header. Expects a comma-delimited string (ex: 'Content-Type,Authorization') or an array (ex: ['Content-Type', 'Authorization']). If not specified, defaults to reflecting the headers specified in the request's Access-Control-Request-Headers header.
exposedHeaders: Configures the Access-Control-Expose-Headers CORS header. Expects a comma-delimited string (ex: 'Content-Range,X-Content-Range') or an array (ex: ['Content-Range', 'X-Content-Range']). If not specified, no custom headers are exposed.
credentials: Configures the Access-Control-Allow-Credentials CORS header. Set to true to pass the header, otherwise it is omitted.
maxAge: Configures the Access-Control-Max-Age CORS header. Set to an integer to pass the header, otherwise it is omitted.
preflightContinue: Pass the CORS preflight response to the route handler (default: false).
optionsSuccessStatus: Provides a status code to use for successful OPTIONS requests, since some legacy browsers (IE11, various SmartTVs) choke on 204.
preflight: if needed you can entirely disable preflight by passing false here (default: true).

Acknowledgements

The code is a port for Fastify of expressjs/cors.

License