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📲A minimal and lightweight JSONP implementation by Promise API
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Better JSONP npm Build Status npm

A minimal and lightweight JSONP implementation which is used to be a kind of cross domain solutions.


  • Implement JSONP request from the browser

  • Combine URL query parameters by default behavior

  • Support the Promise API

  • Limit JSONP request period

  • Handle network error response


# using npm
npm i better-jsonp
# using yarn
yarn add better-jsonp
<!-- using CDN -->
<!-- recommend you to add version number to url ending. eg. -->
<script src=""></script>
<script src=""></script>

Promise polyfill

If your browser doesn't support ES6 Promise, you should import polyfill to the global environment at the beginning of your application.


Notice: Don't assign the result of polyfill() to any variable.


JSONP only support GET methods, same as better-JSONP.

  • The code below show you how to use package as a dependency
// as a request dependency named jsonp
import jsonp from 'better-jsonp'
  url: 'http://localhost',
  // global function named `callback` will be invoked when JSONP response
  jsonpCallback: 'callback', // any different name from request module
  timeout: 5000,
  // eg. ?customCallbackParams=...
  callbackParams: 'customCallbackParams',
  urlParams: {
    // eg. ?key0=0&key1=1...
    key0: 0,
    key1: 1
  .then(res => console.log(res))
  .catch(err => console.error(err))

⚠️ Notice: Parameter jsonpCallback value MUST NOT be same as request module name (eg. dependency named jsonp above code), otherwise request module only works once and function named value of parameter jsonpCallback will be reset to null (internal implementation) which means the same name request module will be also reset unexpectedly.

For more customization capability, This package wouldn't convert jsonpCallback to a new name to prevent unexpected reset.

  • You can also invoke function named jsonp directly in global environment if you have installed package from CDN.(Play on the playground
  // custom configuration

⚠️ Notice: For same reason, parameter jsonpCallback value MUST NOT be jsonp.


options parameter type required description
url String true JSONP request address
timeout Number false, default : 6000 milliseconds how long after timeout error is emitted. 0 to disable
jsonpCallback String false, default : 'callback' global callback function name which is used to handle JSONP response.
callbackParams String false, default: jsonpCallback name of query parameter to specify the callback name
urlParams Object false, default: {} other parameters in query string parameters


  • Uncaught SyntaxError: Unexpected token :error

It mostly doesn't support JSONP request when you are calling a JSON api. The difference between JSON api and JSONP is that JSON api response with an object like { num: 1 } (It will throw a error when client executed this response as a function. ). On the other hand, JSONP will respond with a function wrapped object like jsonpCallback({ num: 1 }) and we will get what we need when client executed this response as a function.

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