node-fetch v2.7.0: punycode is deprecated in 'whatwg-url' and 'tr46'

[spetrac-nicos-ag]

Currently there are several issues raised for node-fetch v2.x (#1793, #1794, #1797) regarding the deprecation of punycode in whatwg-url up until v12.x (#261). There are over 5000 dependents on this module and using any of those packages outputs a deprecation warning regarding punycode.

cross-fetch/src/node-ponyfill.js

Lines 1 to 2 in 1fb2350

	const nodeFetch = require('node-fetch')
	const realFetch = nodeFetch.default || nodeFetch

cross-fetch/src/node-ponyfill.js

Lines 17 to 19 in 1fb2350

	exports.Headers = nodeFetch.Headers
	exports.Request = nodeFetch.Request
	exports.Response = nodeFetch.Response

As a solution I would suggest requiring the node-fetch module only when there is not already a fetch in the global scope (which was already introduced in node v17.5.0 and is stable since v21.0.0).

const nodeFetch = global.fetch || require('node-fetch') 
const realFetch = nodeFetch.default || nodeFetch 

exports.Headers = nodeFetch.Headers || global.Headers
exports.Request = nodeFetch.Request || global.Request
exports.Response = nodeFetch.Response || global.Response

With this everything should be backwards compatible and also upwards compatible with newer node versions. The only thing that might not be included is the agent options for the fetch method to inject a node http agent, but this feature of node-fetch is not a fetch standard anyways.