express-cache-controlfreak

Middleware for ExpressJS that defines a cacheControl method to set Cache-Control headers.

This middleware doesn't define legacy Expires headers. For compatibility with old HTTP/1.0 agents combine it with express-legacy-expires.

Install

$ npm install express-cache-controlfreak

Usage

var cacheControl = require('express-cache-controlfreak');

As Middleware

The function can be used as middleware to set cache control headers in your handler chains.

// Set max age header for this route with the get verb
app.get('/', cacheControl({ maxAge: 300 }), function(req, res, next) {
    res.status(200).json({ success: true })
});

This means you can also easily set app-wide cache-control settings.

// Set default no-cache header for the whole app
app.use(cacheControl('no-cache'));

Chained

The headers can also be set with the chainable cacheControl function that is added to the response object.

app.get('/', function(req, res, next) {
    res.cacheControl({maxAge: 300})
       .status(200)
       .json({ success: true });
});

res.cacheControl([pattern], [options])

The method added by the module accepts an optional string pattern and an object of Cache-Control options. Both are optional but at least one of them should be specified.

See the HTTP/1.1 Standard's Cache-Control sections for information on the usage of Cache-Control directives.

Patterns

String patterns are defined for simple directives so you can simply write res.cacheControl("public"); instead of having to always write res.cacheControl({'public': true});. Properties can be combined with options res.cacheControl("public", {mustRevalidate: true});.

"public"

res.cacheControl("public");
// Cache-Control: public

"private"

res.cacheControl("private");
// Cache-Control: private

"no-cache"

res.cacheControl("no-cache");
// Cache-Control: no-cache

"no-store"

res.cacheControl("no-store");
// Cache-Control: no-cache, no-store

Time Strings and Numbers

The max-age header can be set quickly in a similar manner, using a time string or explicit number. By default, the public directive is also added.

res.cacheControl("1h");
// Cache-Control: public, max-age=3600

res.cacheControl(60);
// Cache-Control: public, max-age=60

Time Strings

Simple time strings can be used for setting the max-age and s-maxage directives. See the ms library, which is used to parse the time string, for the syntax. This is the same library and syntax used by the express sendFile function.

Options

Each Cache-Control response directive defined in HTTP/1.1 has an option that can be defined.

• Options for directives that use a delta time accept a number as a value.
• Options that optionally accept field names accept true for the normal non-field directive and for the with field-name directive accept either a string or an array of strings for the field names.
• The remaining directives that don't have a value simply accept a truthy value.

The public, private, no-cache, and no-store directives are exclusive only one may be specified. With the exception that no-cache and no-store may be defined together.

public:

res.cacheControl({'public': true});
// Cache-Control: public

private:

res.cacheControl({'private': true});
// Cache-Control: private

res.cacheControl({'private': "X-Private"});
// Cache-Control: private="X-Private"

res.cacheControl({'private': ["X-Private-1", "X-Private-2"]});
// Cache-Control: private="X-Private-1, X-Private-2"

no-cache:

res.cacheControl({'no-cache': true});
res.cacheControl({noCache: true});
// Cache-Control: no-cache

res.cacheControl({noCache: "X-Uncached"});
// Cache-Control: no-cache="X-Uncached"

res.cacheControl({noCache: ["X-Uncached-1", "X-Uncached-2"]});
// Cache-Control: no-cache="X-Uncached-1, X-Uncached-2"

no-store:

res.cacheControl({'no-store': true});
res.cacheControl({noStore: true});
// Cache-Control: no-cache, no-store

• no-store also implies no-cache because some browsers have begone treating no-cache the same way they treat no-store.

max-age:

res.cacheControl({'max-age': 300});
res.cacheControl({maxAge: 300});
// Cache-Control: public, max-age=300

• max-age implies public if none of private, no-cache, or no-store is defined, so you can define it alone.

s-maxage:

res.cacheControl({'s-maxage': 300});
res.cacheControl({sMaxage: 300});
res.cacheControl({sMaxAge: 300});
// Cache-Control: public, s-maxage=300

• s-maxage supports sMaxAge in addition to the standard camel-case conversion sMaxage due to the potential confusion of the max-age to maxAge conversion.

must-revalidate:

res.cacheControl({'must-revalidate': true});
res.cacheControl({mustRevalidate: true});
// Cache-Control: must-revalidate

proxy-revalidate:

res.cacheControl({'proxy-revalidate': true});
res.cacheControl({proxyRevalidate: true});
// Cache-Control: proxy-revalidate

no-transform:

res.cacheControl({noTransform: true});
res.cacheControl({'no-transform': true});
// Cache-Control: no-transform

License

MIT