Implement setFetchHandler

packages/api-fetch/README.md

@@ -1,6 +1,6 @@
 # API Fetch
 
-Utility to make WordPress REST API requests. It's a wrapper around `window.fetch`.
+Utility to make WordPress REST API requests. It's a wrapper around `fetch`.
 
 ## Installation
 
@@ -89,7 +89,7 @@ apiFetch.use( apiFetch.createRootURLMiddleware( rootURL ) );
 
 ### Custom fetch handler
 
-The `api-fetch` package uses `window.fetch` for making the requests but you can use a custom fetch handler by using the `setFetchHandler` method. The custom fetch handler will receive the `options` passed to the `apiFetch` calls.
+The `api-fetch` package uses `fetch` for making the requests but you can use a custom fetch handler by using the `setFetchHandler` method. The custom fetch handler will receive the `options` passed to the `apiFetch` calls.
 
 **Example**
 
@@ -111,3 +111,15 @@ apiFetch.setFetchHandler( ( options ) => {
 ```
 
 <br/><br/><p align="center"><img src="https://s.w.org/style/images/codeispoetry.png?1" alt="Code is Poetry." /></p>
+
+### Custom fetch reference
+For polyfilling fetch on Node environment.
+
+**Example**
+
+```js
+import apiFetch from '@wordpress/api-fetch';
+import fetch from 'isomorphic-fetch';
+
+apiFetch.setFetchReference( fetch );
+```

packages/api-fetch/src/index.js

@@ -45,6 +45,17 @@ const middlewares = [
 	fetchAllMiddleware,
 ];
 
+let fetchReference = typeof window !== 'undefined' && 'fetch' in window && typeof window.fetch === 'function' && window.fetch.bind( window );
+
+/**
+ * Defines a custom fetch reference to support fetch on Node
+ *
+ * @param {Function} newFetchReference The new fetch reference
+ */
+function setFetchReference( newFetchReference ) {
+	fetchReference = newFetchReference;
+}
+
 function registerMiddleware( middleware ) {
 	middlewares.unshift( middleware );
 }
@@ -70,7 +81,7 @@ const defaultFetchHandler = ( nextOptions ) => {
 		headers[ 'Content-Type' ] = 'application/json';
 	}
 
-	const responsePromise = window.fetch(
+	const responsePromise = fetchReference(
 		url || path,
 		{
 			...DEFAULT_OPTIONS,
@@ -128,7 +139,7 @@ let fetchHandler = defaultFetchHandler;
 
 /**
  * Defines a custom fetch handler for making the requests that will override
- * the default one using window.fetch
+ * the default one using fetch
  *
  * @param {Function} newFetchHandler The new fetch handler
  */
@@ -158,7 +169,7 @@ function apiFetch( options ) {
 				}
 
 				// If the nonce is invalid, refresh it and try again.
-				window.fetch( apiFetch.nonceEndpoint )
+				fetchReference( apiFetch.nonceEndpoint )
 					.then( checkStatus )
 					.then( ( data ) => data.text() )
 					.then( ( text ) => {
@@ -174,6 +185,7 @@ function apiFetch( options ) {
 
 apiFetch.use = registerMiddleware;
 apiFetch.setFetchHandler = setFetchHandler;
+apiFetch.setFetchReference = setFetchReference;
 
 apiFetch.createNonceMiddleware = createNonceMiddleware;
 apiFetch.createPreloadingMiddleware = createPreloadingMiddleware;