x-middleware-util v1.0.1

x-middleware-util

Build Status](https://travis-ci.org/x-component/x-middleware-util)

• ./condition.js
• ./end.js
• ./error.js
• ./index.js
• ./mode.js
• ./redirect.js
• ./util.js

./condition.js

./end.js

./error.js

./index.js

./mode.js

• bool

bool

Test middleware, checks if differents modes are active e.g. header X-x-template

./redirect.js

./util.js

• url
• undefined.vary()
• undefined.type()
• undefined.rewrite()
• undefined.addHeader()
• setHeader
• undefined.getHeaders()
• writeHead
• undefined.setHeaderFilter():)

url

adds some utility functions to respons and request

undefined.vary()

get a header and add the name to response Vary headers, as the requested header will determine the response content.

Note: besides the header value often also its absence will determine the response content. Therefore the header still should occur in the Vary headers. Only a correct response Vary header allows a correct web caching.

undefined.type()

mix between accept and url matching to check for a specfic request type because accept is offten to wide in accepting results therefore express accept is no good enough p.e. a chrome request will lead to accept image also if it accepts html. While correct the sematics is problematic.

undefined.rewrite()

rewrite the current url to the a new url, adapts also req.query optionally passes previous req.query {query:true}

undefined.addHeader()

add an header value, if a value already exists then add this value to an array of values as node allows multiple header values within an array Note: this is case sensitive, as we can send in node with a specific upper/lower case name. Only values with same case in the name are merged into an array This is done for compatibility. Case should be ignored in HTTP, but some clients and other server don't ignore it. Thereby we should SEND in the common upper/lower case format: Set-Cooke, Content-Type etc.

setHeader

we wrap setHeader to check if some one tries to to set the heder after the response is al ready send this is a common mistake if a pipeline already has ended or there is some where a double next call. The first one sends the repsonse body The wrong second call tries to set headers and/or send again a body Note: the Etag setting of express connect sometimes produces this error

undefined.getHeaders()

get all headers set with their case sensitive names as they where set in node we can receive headers just in lower case, but send them in the case we define

writeHead

wrap writeHead to convert the vary header to a single string if it is an array, as Varnish requires this format and set a header x-o2-set-cookies to inform varnish about all cookie names we set this way varnish doesn't need to parse the single set cookie headers

undefined.setHeaderFilter(name:, filter(name,value):)

this allows the to define a function which is called whenever a setHeader is called. On can therfore change/prevent certain header settings if perfromed by (external) middlewares lateron in the pipeline