koa-jsonp

A koajs streaming friendly JSONP middleware that supports GET/POST JSONP requests.

Install

$ npm install koa-jsonp@next

Example

const db = require('nano')('http://localhost:5984/my_db')
const stringify = require('json-array-stream')
const jsonp = require('koa-jsonp')
 
app.use(jsonp())
 
app.use(mount('/users', async function (ctx) {
  ctx.type = 'json'
  ctx.body = db.view('koa_example', 'users')
    .pipe(JSONStream.parse('rows.*.value'))
    .pipe(stringify())
}))
 
app.use(mount('/dow', async function (ctx) {
  ctx.body = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']
}))
 
app.listen(8080)

yield

GET  http://localhot:8080/users                       -> JSON
POST http://localhot:8080/users                       -> JSON
GET  http://localhot:8080/users?callback=onUserList   -> JSONP
POST http://localhot:8080/users?callback=onUserList   -> JSONP + iFrame

GET  http://localhot:8080/dow                         -> JSON
POST http://localhot:8080/dow                         -> JSON
GET  http://localhot:8080/dow?callback=dowReady       -> JSONP
POST http://localhot:8080/dow?callback=dowReady       -> JSONP + iFrame

API

function jsonp (options)

Returns the koa middleware.

Options

• domain - (String: defaults to '.default.lan') the first level domain where your API will be consumed. Used in iframe mode (???)
• callbackName: (String: defaults to 'callback') The name of the JSONP callback

Use cases

• JSONP: text/javascript
• JSONP + iFrame: text/html

The middleware auto selects the right format based on the presence of callback (querystring) and the HTTP method.

JSONP CORS

This is not required if your frontend and your API run in the same domain or if you set the Access-Control-* headers properly. In this case just use an XMLHttpRequest and don't use this middleware at all. Reference: MDN - HTML5Rocks - SO

There is a way to read a JSONP response after sending a POST request (form) in the browser. The solution is to set an iframe as target of the form (could be hidden). The iframe will load your response page, in this case plain HTML with a script tag and will call your callback using parent.callbackname(data).

This is an old snippet using mootools that creates a form, an iframe, and posts your request. Then dispose everything after executing your callback. You can easily port it to jQuery.

var __requestsMap__ = {}
 
function post(url, fields, callback) {
  var requestId = new Date().getTime()
  var inputs = []
 
  Object.keys(fields).forEach(function (fieldName) {
    inputs.push(new Element('input', {
      name: fieldName,
      value: data[fieldName]
    }))
  })
 
  if (url.match(/\?/)) {
    url += '&callback=__requestsMap__["' + requestId + '"]'
  } else {
    url += '?callback=__requestsMap__["' + requestId + '"]'
  }
 
  var form = new Element('form', {
    'enctype': enctype,
    'method': 'post',
    'action': url,
    'target': requestId,
    'style': 'display: none'
  }).adopt(inputs).inject(document.body)
 
  var iframe = new Element('iframe', {
    id: requestId,
    name: requestId,
    styles: { display: 'none' }
  }).inject(document.body)
 
  __requestsMap__[requestId] = function (response) {
    callback(null, response)
    // cleanup
    delete __requestsMap__[requestId]
    iframe.dispose().destroy()
    form.dispose().destroy()
  }
 
  form.submit()
}

How to contribute

koa-jsonp follows (more or less) the Felix's Node.js Style Guide, your contribution must be consistent with this style.

The test suite is written on top of mochajs/mocha and it took hours of hard work. Please use the tests to check if your contribution is breaking some part of the library and add new tests for each new feature.

⚡ npm test

and for your test coverage

⚡ make test-cov

License

This software is released under the MIT license cited below.

Copyright (c) 2013 Kilian Ciuffolo, me@nailik.org. All Rights Reserved.

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the 'Software'), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.