What is @fastify/cors?
@fastify/cors is a Fastify plugin that enables Cross-Origin Resource Sharing (CORS) for your Fastify application. It allows you to configure how your server handles cross-origin requests, which is essential for enabling web applications to interact with resources from different origins.
What are @fastify/cors's main functionalities?
Enable CORS with default settings
This code demonstrates how to enable CORS with the default settings in a Fastify application. By registering the @fastify/cors plugin without any options, it allows all cross-origin requests.
const fastify = require('fastify')();
const cors = require('@fastify/cors');
fastify.register(cors);
fastify.get('/', (request, reply) => {
reply.send({ hello: 'world' });
});
fastify.listen(3000, err => {
if (err) throw err;
console.log('Server listening on http://localhost:3000');
});
Enable CORS with specific origin
This code demonstrates how to enable CORS for a specific origin. By passing an options object with the 'origin' property set to 'https://example.com', only requests from this origin will be allowed.
const fastify = require('fastify')();
const cors = require('@fastify/cors');
fastify.register(cors, { origin: 'https://example.com' });
fastify.get('/', (request, reply) => {
reply.send({ hello: 'world' });
});
fastify.listen(3000, err => {
if (err) throw err;
console.log('Server listening on http://localhost:3000');
});
Enable CORS with multiple origins
This code demonstrates how to enable CORS for multiple origins. By passing an array of origins to the 'origin' property, requests from any of these origins will be allowed.
const fastify = require('fastify')();
const cors = require('@fastify/cors');
fastify.register(cors, { origin: ['https://example.com', 'https://another-example.com'] });
fastify.get('/', (request, reply) => {
reply.send({ hello: 'world' });
});
fastify.listen(3000, err => {
if (err) throw err;
console.log('Server listening on http://localhost:3000');
});
Enable CORS with custom headers
This code demonstrates how to enable CORS with custom headers. By passing an options object with the 'allowedHeaders' property, you can specify which headers are allowed in cross-origin requests.
const fastify = require('fastify')();
const cors = require('@fastify/cors');
fastify.register(cors, { allowedHeaders: ['Content-Type', 'Authorization'] });
fastify.get('/', (request, reply) => {
reply.send({ hello: 'world' });
});
fastify.listen(3000, err => {
if (err) throw err;
console.log('Server listening on http://localhost:3000');
});
Other packages similar to @fastify/cors
cors
The 'cors' package is a popular middleware for enabling CORS in Express.js applications. It provides similar functionality to @fastify/cors but is designed for use with Express.js rather than Fastify. It allows you to configure CORS settings such as allowed origins, methods, and headers.
koa2-cors
The 'koa2-cors' package is a middleware for enabling CORS in Koa.js applications. Like @fastify/cors, it allows you to configure CORS settings, but it is specifically designed for Koa.js. It supports various options for controlling how cross-origin requests are handled.
hapi-cors
The 'hapi-cors' package is a plugin for enabling CORS in Hapi.js applications. It provides similar functionality to @fastify/cors but is tailored for the Hapi.js framework. It allows you to configure CORS settings such as allowed origins, methods, and headers.
@fastify/cors
![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat)
@fastify/cors
enables the use of CORS in a Fastify application.
Install
npm i @fastify/cors
Compatibility
Plugin version | Fastify version |
---|
^8.0.0 | ^4.0.0 |
^7.0.0 | ^3.0.0 |
^3.0.0 | ^2.0.0 |
^1.0.0 | ^1.0.0 |
Please note that if a Fastify version is out of support, then so are the corresponding version(s) of this plugin
in the table above.
See Fastify's LTS policy for more details.
Usage
Require @fastify/cors
and register it as any other plugin, it will add an onRequest
hook and a wildcard options route.
import Fastify from 'fastify'
import cors from '@fastify/cors'
const fastify = Fastify()
await fastify.register(cors, {
})
fastify.get('/', (req, reply) => {
reply.send({ hello: 'world' })
})
await fastify.listen({ port: 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. The special *
value (default) allows any origin.RegExp
- set origin
to a regular expression pattern that will be used to test the request origin. If it is 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 [Error | null], origin
), where origin
is a non-function value of the origin option. Async-await and promises are supported as well. The Fastify instance is bound to function call and you may access via this
. For example:
origin: (origin, cb) => {
const hostname = new URL(origin).hostname
if(hostname === "localhost"){
cb(null, true)
return
}
cb(new Error("Not allowed"), false)
}
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']
).hook
: See the section Custom Fastify hook name
(default: onRequest
)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. In seconds. Set to an integer to pass the header, otherwise it is omitted.cacheControl
: Configures the Cache-Control header for CORS preflight responses. Set to an integer to pass the header as Cache-Control: max-age=${cacheControl}
, or set to a string to pass the header as Cache-Control: ${cacheControl}
(fully define the header value), otherwise the header is omitted.preflightContinue
: Pass the CORS preflight response to the route handler (default: false
).optionsSuccessStatus
: Provides a status code to use for successful OPTIONS
requests, since some legacy browsers (IE11, various SmartTVs) choke on 204
.preflight
: if needed you can entirely disable preflight by passing false
here (default: true
).strictPreflight
: Enforces strict requirement of the CORS preflight request headers (Access-Control-Request-Method and Origin) as defined by the W3C CORS specification (the current fetch living specification does not define server behavior for missing headers). Preflight requests without the required headers will result in 400 errors when set to true
(default: true
).hideOptionsRoute
: hide options route from the documentation built using @fastify/swagger (default: true
).
Configuring CORS Asynchronously
const fastify = require('fastify')()
fastify.register(require('@fastify/cors'), (instance) => {
return (req, callback) => {
const corsOptions = {
origin: true
};
if (/^localhost$/m.test(req.headers.origin)) {
corsOptions.origin = false
}
callback(null, corsOptions)
}
})
fastify.register(async function (fastify) {
fastify.get('/', (req, reply) => {
reply.send({ hello: 'world' })
})
})
fastify.listen({ port: 3000 })
Custom Fastify hook name
By default, @fastify/cors
adds a onRequest
hook where the validation and header injection are executed. This can be customized by passing hook
in the options. Valid values are onRequest
, preParsing
, preValidation
, preHandler
, preSerialization
, and onSend
.
import Fastify from 'fastify'
import cors from '@fastify/cors'
const fastify = Fastify()
await fastify.register(cors, {
hook: 'preHandler',
})
fastify.get('/', (req, reply) => {
reply.send({ hello: 'world' })
})
await fastify.listen({ port: 3000 })
When configuring CORS asynchronously, an object with delegator
key is expected:
const fastify = require('fastify')()
fastify.register(require('@fastify/cors'), {
hook: 'preHandler',
delegator: (req, callback) => {
const corsOptions = {
origin: true
};
if (/^localhost$/m.test(req.headers.origin)) {
corsOptions.origin = false
}
callback(null, corsOptions)
},
})
fastify.register(async function (fastify) {
fastify.get('/', (req, reply) => {
reply.send({ hello: 'world' })
})
})
fastify.listen({ port: 3000 })
Acknowledgements
The code is a port for Fastify of expressjs/cors
.
License
Licensed under MIT.
expressjs/cors
license