Switched fetch client from 'node-fetch' to 'make-fetch-happen' and ad…

.prettierignore

@@ -0,0 +1 @@
+package-lock.json

README.md

@@ -2,6 +2,19 @@
 
 A [nodejs loader](https://nodejs.org/dist/latest-v13.x/docs/api/esm.html#esm_experimental_loaders) for loading modules over the network with http/https.
 
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+
+**Table of Contents** _generated with [DocToc](https://github.com/thlorenz/doctoc) (`npx doctoc README.md`)_
+
+- [Installation](#installation)
+- [Usage](#usage)
+  - [Configure cache behaviour](#configure-cache-behaviour)
+- [Semantics](#semantics)
+- [Composition](#composition)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
 ## Installation
 
 ```sh
@@ -27,11 +40,20 @@ Now run node with the `--experimental-loader` flag:
 node --experimental-loader @node-loader/http file.js
 ```
 
+### Configure cache behaviour
+
+Override default `make-fetch-happen` [options](https://github.com/npm/make-fetch-happen#--make-fetch-happen-options) via specifying the `HTTP_IMPORT_CACHING` (`opts.cache`) environment variable, and/or the `HTTP_IMPORT_CACHDIR` (`opts.cachePath`) environment variable.
+
+```sh
+HTTP_IMPORT_CACHING=default \
+HTTP_IMPORT_CACHDIR=.local-cache \
+node --experimental-loader @node-loader/http file.js
+```
+
 ## Semantics
 
-This project uses [node-fetch](https://github.com/node-fetch/node-fetch) to implement familiar HTTP semantics,
-including http redirects, https redirects, HTTP status checks, etc. Customizing the behavior of node-fetch is
-planned, but not yet implemented.
+This project uses [make-fetch-happen](https://github.com/npm/make-fetch-happen) to implement familiar HTTP semantics,
+including http redirects, https redirects, HTTP status checks, etc.
 
 ## Composition
 

lib/node-loader-http.js

@@ -1,4 +1,40 @@
-import fetch from "node-fetch";
+import fetch from "make-fetch-happen";
+import path from "path";
+import { homedir } from "os";
+
+const HTTP_IMPORT_CACHING = process.env.HTTP_IMPORT_CACHING || "default";
+
+const allowedStrategies = [
+  "default",
+  "no-store",
+  "reload",
+  "no-cache",
+  "force-cache",
+  "only-if-cached",
+];
+
+if (!allowedStrategies.includes(HTTP_IMPORT_CACHING)) {
+  throw new Error(
+    `Incorrect HTTP_IMPORT_CACHING value "${HTTP_IMPORT_CACHING}". Please refer to make-fetch-happen documentation https://github.com/npm/make-fetch-happen#--optscache for allowed values`
+  );
+}
+
+const HTTP_IMPORT_CACHDIR =
+  process.env.HTTP_IMPORT_CACHDIR ||
+  (process.platform === "darwin"
+    ? path.join(homedir(), "Library", "Caches", "node-loader-http")
+    : process.platform === "win32"
+    ? path.join(
+        process.env.LOCALAPPDATA || path.join(homedir(), "AppData", "Local"),
+        "node-loader-http-cache"
+      )
+    : path.join(
+        process.env.XDG_CACHE_HOME || path.join(homedir(), ".cache"),
+        "node-loader-http"
+      ));
+
+console.info("@node-loader/http", "cache =", HTTP_IMPORT_CACHING);
+console.info("@node-loader/http", "cachePath =", HTTP_IMPORT_CACHDIR);
 
 export function resolve(specifier, context, defaultResolve) {
   const { parentURL = null } = context;
@@ -46,7 +82,10 @@ export async function load(url, context, defaultLoad) {
 
     let source;
 
-    const httpResponse = await fetch(url);
+    const httpResponse = await fetch(url, {
+      cachePath: HTTP_IMPORT_CACHDIR,
+      cache: HTTP_IMPORT_CACHING,
+    });
 
     if (httpResponse.ok) {
       source = await httpResponse.text();