patch-headers

patch-headers

Express middleware to patch response headers written by another handler or middleware.

Usage

The module returns a function to build a middleware. The function must be called with a single options object with one or more of the following properties:

• allow: An array that contains a whitelist of header names.
• remove: An array that contains a blacklist of header names.
• static: An object with key value pairs of static header names and values.
• callback: A function which has a single object parameter for the header key value pairs and returns an object in the same format.

Priority:

• If allow is set, all headers other than the ones in allow are removed
• If remove is set, all headers in remove are removed
• If static is set, all key: value in static are added
• If callback is set, all key: value in callback(headers) are added

By this logic, using a combination of allow and remove doesn't make much sense.

Example

// load the module
const patchHeaders = require('patchHeaders')

// add the routing
app.use(patchHeaders({
  allow: ['Content-Length', 'Content-Type'],
  static: {
    'Access-Control-Allow-Origin': '*'
  },
  callback (headers) {
    return {
      'Content-Length': headers['Content-Length'] + Math.random()
    }
  }
})