簡潔易用的基於Promise的jsonp庫easy-jsonp，瞭解下

如今流行的axios庫不支持jsonp，所以這裏推薦一個jsonp庫，簡單易用。如下是介紹：

Easy JSONP

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

Features

• 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

Install

# using npm
npm i easy-jsonp

# using yarn
yarn add easy-jsonp

# using script target
<script src="jsonp.js"></script>

Usage

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

• The code below show you how to use package as a dependency

// as a request dependency named jsonp
import jsonp from 'easy-jsonp'
const jsonp = require('easy-jsonp').default

jsonp({
  url: 'http://localhost',
  // global function named `callback` will be invoked when JSONP response
  callback: 'callback', // any different name from request module
  timeout: 3000,
  params: {
    // eg. ?key0=0&key1=1...
    key0: 0,
    key1: 1
  }
})
  .then(res => console.log(res))
  .catch(err => console.error(err))

⚠️ Notice: Parameter callback 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 callback 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 callback to a new name to prevent unexpected reset.

jsonp({
  // custom configuration
})

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

Parameters

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
callback	String	false, default : 'jsonpCallback'+Date.now()	global callback function name which is used to handle JSONP response.
params	Object	false, default: {}	other parameters in query string parameters

Notice

• 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 callback({ num: 1 }) and we will get what we need when client executed this response as a function.