docs: update in-code docs

lib/fetch/util.js

@@ -284,7 +284,6 @@ function clonePolicyContainer () {
 
 // https://w3c.github.io/webappsec-referrer-policy/#determine-requests-referrer
 function determineRequestsReferrer (request) {
-  // TODO
   // 1. Let policy be request's referrer policy.
   const policy = request.referrerPolicy
 
@@ -297,14 +296,29 @@ function determineRequestsReferrer (request) {
   const environment = request.client
   let referrerSource = null
 
-  // TODO
-  // 3(a) If policy is "origin", then
-  // 3(a)(I) If environment's global object is Window then
+  /**
+   * 3, Switch on request’s referrer:
+    "client"
+      If environment’s global object is a Window object, then
+        Let document be the associated Document of environment’s global object.
+        If document’s origin is an opaque origin, return no referrer.
+        While document is an iframe srcdoc document,
+        let document be document’s browsing context’s browsing context container’s node document.
+        Let referrerSource be document’s URL.
+
+      Otherwise, let referrerSource be environment’s creation URL.
+
+    a URL
+    Let referrerSource be request’s referrer.
+   */
   if (request.referrer === 'client') {
     if (environment?.globalObject instanceof Window) {
       const origin = environment.globalObject.self?.origin ?? environment.globalObject.location?.origin
 
+      // If document’s origin is an opaque origin, return no referrer.
       if (origin == null || origin === 'null') return 'no-referrer'
+
+      // Let referrerSource be document’s URL.
       referrerSource = new URL(environment.globalObject.location.href)
     } else {
       // 3(a)(II) If environment's global object is not Window,