This is a small extenstion to Richard Schneider's express-preconditions package.

Middleware for HTTP Conditional Requests (RFC 7232). It conditionally processes a HTTP request based on a precondition (such as an etag or modification date). A precondition is specified using the If-Match, If-None-Match, If-Modified-Since or If-Unmodified-Since HTTP header.

The change log is automatically produced with the help of semantic-release.

Install with npm

> npm install express-preconditions-addl --save

Include the following in your server startup

    const preconditions = require('express-preconditions-addl')
    app.use(preconditions())

or

    const preconditions = require('express-preconditions-addl')
    const options = { ... }
    app.use(preconditions(options))

See our test server for more details.

The resource state contains the etag and lastModified properties, which conform to the respective HTTP headers and can be undefined.

The default stateAsync() obtains the resource state by sending a HEAD request to the server.

The following HTTP status codes can be returned by the middleware

• The If-Range header is not currently supported.

The MIT license.