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fetch-jsonp-polyfill

library1.1.5jsnpmunverified

A polyfill that adds JSONP support to the Fetch API by allowing method: 'JSONP' in fetch options. Current stable version is 1.1.5 (not updated since 2016). It wraps existing fetch polyfills like github/fetch, isomorphic-fetch, or node-fetch and must be imported after them. Unlike alternatives, it does not expose a separate JSONP function but monkey-patches the global fetch to transparently handle JSONP requests when the method is set to 'JSONP'. Supports common JSONP options: timeout, callback query parameter name, and callback function name.

testing

npm install fetch-jsonp-polyfill

package ↗

INSTALL

IMPORT

SIG · FETCH-JSONP-POLYFI

fetch-jsonp-polyfill

testingjavascriptv1.1.5

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

fetch-jsonp-polyfill (side-effect import)

✓ import 'fetch-jsonp-polyfill'

✗ import fetchJsonp from 'fetch-jsonp-polyfill'

This package is a side-effect polyfill that modifies the global fetch. It does not export any symbols.

require (CommonJS)

✓ require('fetch-jsonp-polyfill')

✗ const fetchJsonp = require('fetch-jsonp-polyfill')

In CommonJS, assign the require to a variable is misleading because no value is exported. Just call require without assignment.

import order

✓ import 'isomorphic-fetch'; import 'fetch-jsonp-polyfill'

✗ import 'fetch-jsonp-polyfill'; import 'isomorphic-fetch'

Must import the base fetch polyfill (e.g., isomorphic-fetch) before this polyfill, otherwise JSONP requests will fail.

Shows how to use the polyfill: import after a base fetch polyfill, then call fetch with method:'JSONP' and optional JSONP-specific options.

// Install: npm install fetch-jsonp-polyfill isomorphic-fetch import 'isomorphic-fetch'; import 'fetch-jsonp-polyfill'; const URL = 'http://jsfiddle.net/echo/jsonp/'; fetch(URL, { method: 'JSONP', timeout: 5000, callback: 'callback', callbackName: 'fetchjsonp_callback' }) .then(res => res.json()) .then(data => { console.log('JSONP response:', data); }) .catch(err => { console.error('JSONP error:', err); });

Debug

Known issues

deprecatedThe package has not been updated since 2016 and is effectively deprecated. Use without active maintenance.

fix

Consider using a maintained solution like fetch-jsonp (npm package 'fetch-jsonp') which exports a standalone function.

affects: >=1.0.0

breakingGlobal fetch polyfill must be imported BEFORE fetch-jsonp-polyfill, otherwise fetch may be undefined or lack polyfill methods.

fix

Ensure any fetch polyfill (e.g., isomorphic-fetch, whatwg-fetch) is imported first.

affects: >=1.0.0

gotchaUsing method:'JSONP' will cause CORS-like preflight errors if the server does not support JSONP. JSONP is inherently insecure (XSS vector) and only uses GET.

fix

Only use JSONP with trusted third-party APIs; prefer CORS-enabled endpoints and standard fetch.

affects: >=1.0.0

gotchaThe polyfill modifies global fetch. In Node.js environment, node-fetch must be polyfilled first.

fix

If using in Node, install and import node-fetch before this polyfill. Read README for compatible polyfills.

affects: >=1.0.0

Errors

Common errors & fixes

Uncaught TypeError: fetch is not a function

Missing a base fetch polyfill (e.g., isomorphic-fetch) or import order reversed.

fix

Install and import a fetch polyfill before fetch-jsonp-polyfill: import 'isomorphic-fetch'; import 'fetch-jsonp-polyfill';

fetch(...).then(res => res.json()) is not a function

JSONP response is not standard JSON but wrapped in a function call; the polyfill does not unwrap it.

fix

You may need to parse the response manually or use a different library that handles JSONP response extraction.

Upgrade

Version history

1.1.5latest on npm

Audit

Dependencies

whatwg-fetchrequiredSuggested as a base fetch polyfill for browser environments; fetch-jsonp-polyfill depends on a global fetch implementation.

Agent activity

2 hits · last 30 days

node

Resources

packagefetch-jsonp-polyfill ↗