5 files changed, 75 insertions, 33 deletions
diff --git a/ext/fetch/20_headers.js b/ext/fetch/20_headers.js
index b99758de5..d03751d08 100644
--- a/ext/fetch/20_headers.js
+++ b/ext/fetch/20_headers.js
@@ -26,7 +26,9 @@ const {
   ArrayPrototypeSort,
   ArrayPrototypeJoin,
   ArrayPrototypeSplice,
+  ObjectFromEntries,
   ObjectHasOwn,
+  ObjectPrototypeIsPrototypeOf,
   RegExpPrototypeTest,
   Symbol,
   SymbolFor,
@@ -441,13 +443,14 @@ class Headers {
     }
   }
 
-  [SymbolFor("Deno.privateCustomInspect")](inspect) {
-    const headers = {};
-    // deno-lint-ignore prefer-primordials
-    for (const header of this) {
-      headers[header[0]] = header[1];
+  [SymbolFor("Deno.privateCustomInspect")](inspect, inspectOptions) {
+    if (ObjectPrototypeIsPrototypeOf(HeadersPrototype, this)) {
+      return `${this.constructor.name} ${
+        inspect(ObjectFromEntries(this), inspectOptions)
+      }`;
+    } else {
+      return `${this.constructor.name} ${inspect({}, inspectOptions)}`;
     }
-    return `Headers ${inspect(headers)}`;
   }
 }
 
diff --git a/ext/fetch/21_formdata.js b/ext/fetch/21_formdata.js
index 84d31898e..12ce2bb58 100644
--- a/ext/fetch/21_formdata.js
+++ b/ext/fetch/21_formdata.js
@@ -26,10 +26,12 @@ const {
   MapPrototypeSet,
   MathRandom,
   ObjectFreeze,
+  ObjectFromEntries,
   ObjectPrototypeIsPrototypeOf,
   SafeMap,
   SafeRegExp,
   Symbol,
+  SymbolFor,
   StringFromCharCode,
   StringPrototypeCharCodeAt,
   StringPrototypeTrim,
@@ -262,6 +264,16 @@ class FormData {
       ArrayPrototypePush(list, entry);
     }
   }
+
+  [SymbolFor("Deno.privateCustomInspect")](inspect, inspectOptions) {
+    if (ObjectPrototypeIsPrototypeOf(FormDataPrototype, this)) {
+      return `${this.constructor.name} ${
+        inspect(ObjectFromEntries(this), inspectOptions)
+      }`;
+    } else {
+      return `${this.constructor.name} ${inspect({}, inspectOptions)}`;
+    }
+  }
 }
 
 webidl.mixinPairIterable("FormData", FormData, entryList, "name", "value");
diff --git a/ext/fetch/23_request.js b/ext/fetch/23_request.js
index bbaf886a6..b78ed07be 100644
--- a/ext/fetch/23_request.js
+++ b/ext/fetch/23_request.js
@@ -483,18 +483,21 @@ class Request {
     );
   }
 
-  [SymbolFor("Deno.customInspect")](inspect) {
-    return inspect(createFilteredInspectProxy({
-      object: this,
-      evaluate: ObjectPrototypeIsPrototypeOf(RequestPrototype, this),
-      keys: [
-        "bodyUsed",
-        "headers",
-        "method",
-        "redirect",
-        "url",
-      ],
-    }));
+  [SymbolFor("Deno.privateCustomInspect")](inspect, inspectOptions) {
+    return inspect(
+      createFilteredInspectProxy({
+        object: this,
+        evaluate: ObjectPrototypeIsPrototypeOf(RequestPrototype, this),
+        keys: [
+          "bodyUsed",
+          "headers",
+          "method",
+          "redirect",
+          "url",
+        ],
+      }),
+      inspectOptions,
+    );
   }
 }
 
diff --git a/ext/fetch/23_response.js b/ext/fetch/23_response.js
index 83fad403a..0b37c1229 100644
--- a/ext/fetch/23_response.js
+++ b/ext/fetch/23_response.js
@@ -408,21 +408,24 @@ class Response {
     return second;
   }
 
-  [SymbolFor("Deno.customInspect")](inspect) {
-    return inspect(createFilteredInspectProxy({
-      object: this,
-      evaluate: ObjectPrototypeIsPrototypeOf(ResponsePrototype, this),
-      keys: [
-        "body",
-        "bodyUsed",
-        "headers",
-        "ok",
-        "redirected",
-        "status",
-        "statusText",
-        "url",
-      ],
-    }));
+  [SymbolFor("Deno.privateCustomInspect")](inspect, inspectOptions) {
+    return inspect(
+      createFilteredInspectProxy({
+        object: this,
+        evaluate: ObjectPrototypeIsPrototypeOf(ResponsePrototype, this),
+        keys: [
+          "body",
+          "bodyUsed",
+          "headers",
+          "ok",
+          "redirected",
+          "status",
+          "statusText",
+          "url",
+        ],
+      }),
+      inspectOptions,
+    );
   }
 }
 
diff --git a/ext/fetch/27_eventsource.js b/ext/fetch/27_eventsource.js
index 6e35bb693..1db65d748 100644
--- a/ext/fetch/27_eventsource.js
+++ b/ext/fetch/27_eventsource.js
@@ -5,6 +5,7 @@
 const core = globalThis.Deno.core;
 
 import * as webidl from "ext:deno_webidl/00_webidl.js";
+import { createFilteredInspectProxy } from "ext:deno_console/01_console.js";
 import { URL } from "ext:deno_url/00_url.js";
 import DOMException from "ext:deno_web/01_dom_exception.js";
 import {
@@ -25,6 +26,7 @@ const {
   NumberIsFinite,
   NumberIsNaN,
   ObjectDefineProperties,
+  ObjectPrototypeIsPrototypeOf,
   Promise,
   StringPrototypeEndsWith,
   StringPrototypeIncludes,
@@ -34,6 +36,7 @@ const {
   StringPrototypeStartsWith,
   StringPrototypeToLowerCase,
   Symbol,
+  SymbolFor,
 } = primordials;
 
 // Copied from https://github.com/denoland/deno_std/blob/e0753abe0c8602552862a568348c046996709521/streams/text_line_stream.ts#L20-L74
@@ -345,6 +348,24 @@ class EventSource extends EventTarget {
       }
     }
   }
+
+  [SymbolFor("Deno.privateCustomInspect")](inspect, inspectOptions) {
+    return inspect(
+      createFilteredInspectProxy({
+        object: this,
+        evaluate: ObjectPrototypeIsPrototypeOf(EventSourcePrototype, this),
+        keys: [
+          "readyState",
+          "url",
+          "withCredentials",
+          "onopen",
+          "onmessage",
+          "onerror",
+        ],
+      }),
+      inspectOptions,
+    );
+  }
 }
 
 const EventSourcePrototype = EventSource.prototype;