fetch-jsonp

library1.4.0jsnpmunverified

A library that provides a JSONP fetch API similar to the standard Fetch API, with support for custom callback parameter names, callback function names, timeouts, fetchPriority, and crossorigin attributes. Version 1.4.0 is the latest stable release. It is lightweight and aims to fill the gap where standard Fetch does not support JSONP. Suitable for older browsers or APIs that still use JSONP, with built-in TypeScript types.

networking

npm install fetch-jsonp

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · FETCH-JSONP

fetch-jsonp

networkingjavascriptv1.4.0

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.

fetchJsonp

✓ import fetchJsonp from 'fetch-jsonp'

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

The package provides a default export. In CommonJS environments, use require('fetch-jsonp').default if using ES interop, but for a simpler CJS import, fetchJsonp is directly available via require with Node's automatic interop.

FetchJsonpOptions

✓ import type { FetchJsonpOptions } from 'fetch-jsonp'

✗ import { FetchJsonpOptions } from 'fetch-jsonp'

FetchJsonpOptions is a TypeScript type, not a runtime value. Use a type import to avoid bundling issues.

FetchJsonpResponse

✓ import type { FetchJsonpResponse } from 'fetch-jsonp'

FetchJsonpResponse is a TypeScript type. Use type import.

Simple JSONP fetch with custom callback parameter and timeout, parsing JSON response.

import fetchJsonp from 'fetch-jsonp'; fetchJsonp('https://api.example.com/data.jsonp', { jsonpCallback: 'cb', timeout: 3000 }) .then(function(response) { return response.json(); }) .then(function(json) { console.log('parsed json', json); }) .catch(function(ex) { console.log('parsing failed', ex); });

Debug

Known issues

gotchafetch-jsonp only supports GET requests, as JSONP inherently requires GET.

fix

Use standard fetch or XMLHttpRequest for POST requests.

affects: >=1.0.0

deprecatedThe option 'jsonpCallbackFunction' is not deprecated but can be confusing; prefer using 'jsonpCallback' to set the query parameter name and let the library generate a unique callback function name.

fix

Use jsonpCallback to set the query parameter name, and avoid manually setting jsonpCallbackFunction unless you have a fixed callback function name requirement.

affects: >=1.0.0

gotchaThe response.json() method returns a Promise that resolves with the parsed JSON data, but the response object's other methods (like text, blob) are not implemented. Attempting to call them will throw an error.

fix

Only use response.json() to parse the JSONP response. Do not call response.text(), response.blob(), etc.

affects: >=1.0.0

breakingIn older versions (<1.0), the default export was a function that required manual callback handling. The v1 release changed to a Fetch-like promise-based API.

fix

Upgrade to >=1.0 and migrate code to use the promise-based API with .then() and .catch().

affects: <1.0.0

gotchafetch-jsonp does not support HTTP redirect following; the script tag used internally does not follow redirects.

fix

Ensure the JSONP endpoint URL is the final URL (no redirects) or handle redirects on the server side.

affects: >=1.0.0

Errors

Common errors & fixes

fetchJsonp is not defined

Incorrect import; in CommonJS, require returns the module correctly but if using ES modules without proper default export handling, the variable may be undefined.

fix

Use import fetchJsonp from 'fetch-jsonp' for ES modules, or const fetchJsonp = require('fetch-jsonp') for CommonJS (Node handles interop).

response.json is not a function

The response object from fetchJsonp only has a json() method; other methods like text(), blob() are not available.

fix

Only call response.json() on the returned response.

TypeError: Failed to fetch

The JSONP script failed to load due to network error, incorrect URL, or the endpoint does not support JSONP.

fix

Verify the URL is correct and the server returns a valid JSONP response (callback wrapped). Check for CORS issues or network connectivity.

Uncaught SyntaxError: Unexpected token

The server response is not valid JSONP (not wrapped in a callback function, or the callback name does not match).

fix

Ensure the server responds with the expected callback function name (e.g., jsonp_xxxx). Use jsonpCallback option to set the query parameter name that the server expects.

Upgrade

Version history

1.4.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

10 hits · last 30 days

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Resources

githubhttps://github.com/camsong/fetch-jsonp ↗

packagefetch-jsonp ↗

homepagehttps://github.com/camsong/fetch-jsonp#readme ↗