# cookie

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Basic HTTP cookie parser and serializer for HTTP servers.

## Installation

```sh
$ npm install cookie
```

## API

```js
var cookie = require('cookie');
```

### cookie.parse(str, options)

Parse an HTTP `Cookie` header string and returning an object of all cookie name-value pairs.
The `str` argument is the string representing a `Cookie` header value and `options` is an
optional object containing additional parsing options.

```js
var cookies = cookie.parse('foo=bar; equation=E%3Dmc%5E2');
// { foo: 'bar', equation: 'E=mc^2' }
```

#### Options

`cookie.parse` accepts these properties in the options object.

##### decode

Specifies a function that will be used to decode a cookie's value. Since the value of a cookie
has a limited character set (and must be a simple string), this function can be used to decode
a previously-encoded cookie value into a JavaScript string or other object.

The default function is the global `decodeURIComponent`, which will decode any URL-encoded
sequences into their byte representations.

**note** if an error is thrown from this function, the original, non-decoded cookie value will
be returned as the cookie's value.

### cookie.serialize(name, value, options)

Serialize a cookie name-value pair into a `Set-Cookie` header string. The `name` argument is the
name for the cookie, the `value` argument is the value to set the cookie to, and the `options`
argument is an optional object containing additional serialization options.

```js
var setCookie = cookie.serialize('foo', 'bar');
// foo=bar
```

#### Options

`cookie.serialize` accepts these properties in the options object.

##### domain

Specifies the value for the [`Domain` `Set-Cookie` attribute][rfc-6266-5.2.3]. By default, no
domain is set, and most clients will consider the cookie to apply to only the current domain.

##### encode

Specifies a function that will be used to encode a cookie's value. Since value of a cookie
has a limited character set (and must be a simple string), this function can be used to encode
a value into a string suited for a cookie's value.

The default function is the global `ecodeURIComponent`, which will encode a JavaScript string
into UTF-8 byte sequences and then URL-encode any that fall outside of the cookie range.

##### expires

Specifies the `Date` object to be the value for the [`Expires` `Set-Cookie` attribute][rfc-6266-5.2.1].
By default, no expiration is set, and most clients will consider this a "non-persistent cookie" and
will delete it on a condition like exiting a web browser application.

**note** the [cookie storage model specification][rfc-6266-5.3] states that if both `expires` and
`magAge` are set, then `maxAge` takes precedence, but it is possiblke not all clients by obey this,
so if both are set, they should point to the same date and time.

##### httpOnly

Specifies the `boolean` value for the [`HttpOnly` `Set-Cookie` attribute][rfc-6266-5.2.6]. When truthy,
the `HttpOnly` attribute is set, otherwise it is not. By default, the `HttpOnly` attribute is not set.

**note** be careful when setting this to `true`, as compliant clients will not allow client-side
JavaScript to see the cookie in `document.cookie`.

##### maxAge

Specifies the `number` (in seconds) to be the value for the [`Max-Age` `Set-Cookie` attribute][rfc-6266-5.2.2].
The given number will be converted to an integer by rounding down. By default, no maximum age is set.

**note** the [cookie storage model specification][rfc-6266-5.3] states that if both `expires` and
`magAge` are set, then `maxAge` takes precedence, but it is possiblke not all clients by obey this,
so if both are set, they should point to the same date and time.

##### path

Specifies the value for the [`Path` `Set-Cookie` attribute][rfc-6266-5.2.4]. By default, the path
is considered the ["default path"][rfc-6266-5.1.4]. By default, no maximum age is set, and most
clients will consider this a "non-persistent cookie" and will delete it on a condition like exiting
a web browser application.

##### sameSite

Specifies the `boolean` or `string` to be the value for the [`SameSite` `Set-Cookie` attribute][draft-west-first-party-cookies-07].

  - `true` will set the `SameSite` attribute to `Strict` for strict same site enforcement.
  - `false` will not set the `SameSite` attribute.
  - `'lax'` will set the `SameSite` attribute to `Lax` for lax same site enforcement.
  - `'strict'` will set the `SameSite` attribute to `Strict` for strict same site enforcement.

More information about the different enforcement levels can be found in the specification
https://tools.ietf.org/html/draft-west-first-party-cookies-07#section-4.1.1

**note** This is an attribute that has not yet been fully standardized, and may change in the future.
This also means many clients may ignore this attribute until they understand it.

##### secure

Specifies the `boolean` value for the [`Secure` `Set-Cookie` attribute][rfc-6266-5.2.5]. When truthy,
the `Secure` attribute is set, otherwise it is not. By default, the `Secure` attribute is not set.

**note** be careful when setting this to `true`, as compliant clients will not send the cookie back to
the server in the future if the browser does not have an HTTPS connection.

## Example

The following example uses this module in conjunction with the Node.js core HTTP server
to prompt a user for their name and display it back on future visits.

```js
var cookie = require('cookie');
var escapeHtml = require('escape-html');
var http = require('http');
var url = require('url');

function onRequest(req, res) {
  // Parse the query string
  var query = url.parse(req.url, true, true).query;

  if (query && query.name) {
    // Set a new cookie with the name
    res.setHeader('Set-Cookie', cookie.serialize('name', String(query.name), {
      httpOnly: true,
      maxAge: 60 * 60 * 24 * 7 // 1 week
    }));

    // Redirect back after setting cookie
    res.statusCode = 302;
    res.setHeader('Location', req.headers.referer || '/');
    res.end();
    return;
  }

  // Parse the cookies on the request
  var cookies = cookie.parse(req.headers.cookie || '');

  // Get the visitor name set in the cookie
  var name = cookies.name;

  res.setHeader('Content-Type', 'text/html; charset=UTF-8');

  if (name) {
    res.write('<p>Welcome back, <b>' + escapeHtml(name) + '</b>!</p>');
  } else {
    res.write('<p>Hello, new visitor!</p>');
  }

  res.write('<form method="GET">');
  res.write('<input placeholder="enter your name" name="name"> <input type="submit" value="Set Name">');
  res.end('</form');
}

http.createServer(onRequest).listen(3000);
```

## Testing

```sh
$ npm test
```

## References

- [RFC 6266: HTTP State Management Mechanism][rfc-6266]
- [Same-site Cookies][draft-west-first-party-cookies-07]

[draft-west-first-party-cookies-07]: https://tools.ietf.org/html/draft-west-first-party-cookies-07
[rfc-6266]: https://tools.ietf.org/html/rfc6266
[rfc-6266-5.1.4]: https://tools.ietf.org/html/rfc6266#section-5.1.4
[rfc-6266-5.2.1]: https://tools.ietf.org/html/rfc6266#section-5.2.1
[rfc-6266-5.2.2]: https://tools.ietf.org/html/rfc6266#section-5.2.2
[rfc-6266-5.2.3]: https://tools.ietf.org/html/rfc6266#section-5.2.3
[rfc-6266-5.2.4]: https://tools.ietf.org/html/rfc6266#section-5.2.4
[rfc-6266-5.3]: https://tools.ietf.org/html/rfc6266#section-5.3

## License

[MIT](LICENSE)

[npm-image]: https://img.shields.io/npm/v/cookie.svg
[npm-url]: https://npmjs.org/package/cookie
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[node-version-url]: https://nodejs.org/en/download
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[travis-url]: https://travis-ci.org/jshttp/cookie
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[coveralls-url]: https://coveralls.io/r/jshttp/cookie?branch=master
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[downloads-url]: https://npmjs.org/package/cookie