CORS is a node.js package for providing a [connect](http://www.senchalabs.org/connect/)/[express](http://expressjs.com/) middleware that can be used to enable [CORS](http://en.wikipedia.org/wiki/Cross-origin_resource_sharing) with various options. Learn more about the project in [the README](README.md).
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
CORS is a node.js package for providing a [Connect](http://www.senchalabs.org/connect/)/[Express](http://expressjs.com/) middleware that can be used to enable [CORS](http://en.wikipedia.org/wiki/Cross-origin_resource_sharing) with various options.
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res.json({msg:'This is CORS-enabled for a whitelisted domain.'});
});
app.listen(80,function(){
console.log('CORS-enabled web server listening on port 80');
});
```
## Configuration Options
*`origin`: Configures the **Access-Control-Allow-Origin** CORS header. Possible values:
-`Boolean` - set `origin` to `true` to reflect the [request origin](http://tools.ietf.org/html/draft-abarth-origin-09), as defined by `req.header('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 (which expects the signature `err [object], allow [bool]`) as the second.
*`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 next handler.
The default configuration is the equivalent of:
```json
{
"origin":"*",
"methods":"GET,HEAD,PUT,PATCH,POST,DELETE",
"preflightContinue":false
}
```
For details on the effect of each CORS header, read [this](http://www.html5rocks.com/en/tutorials/cors/) article on HTML5 Rocks.
## Demo
A demo that illustrates CORS working (and not working) using jQuery is available here: [http://node-cors-client.herokuapp.com/](http://node-cors-client.herokuapp.com/)
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