4 files changed, 36 insertions, 3 deletions
diff --git a/runtime/js/13_buffer.js b/runtime/js/13_buffer.js
index 36d979e75..cac1a6694 100644
--- a/runtime/js/13_buffer.js
+++ b/runtime/js/13_buffer.js
@@ -4,7 +4,7 @@
 // Copyright 2009 The Go Authors. All rights reserved. BSD license.
 // https://github.com/golang/go/blob/master/LICENSE
 
-import { primordials } from "ext:core/mod.js";
+import { internals, primordials } from "ext:core/mod.js";
 const {
   ArrayBufferPrototypeGetByteLength,
   TypedArrayPrototypeSubarray,
@@ -45,6 +45,11 @@ class Buffer {
   #off = 0; // read at buf[off], write at buf[buf.byteLength]
 
   constructor(ab) {
+    internals.warnOnDeprecatedApi(
+      "new Deno.Buffer()",
+      new Error().stack,
+      "Use `Buffer` from `https://deno.land/std/io/buffer.ts` instead.",
+    );
     if (ab == null) {
       this.#buf = new Uint8Array(0);
       return;
@@ -230,18 +235,33 @@ class Buffer {
 }
 
 async function readAll(r) {
+  internals.warnOnDeprecatedApi(
+    "Deno.readAll()",
+    new Error().stack,
+    "Use `readAll()` from `https://deno.land/std/io/read_all.ts` instead.",
+  );
   const buf = new Buffer();
   await buf.readFrom(r);
   return buf.bytes();
 }
 
 function readAllSync(r) {
+  internals.warnOnDeprecatedApi(
+    "Deno.readAllSync()",
+    new Error().stack,
+    "Use `readAllSync()` from `https://deno.land/std/io/read_all.ts` instead.",
+  );
   const buf = new Buffer();
   buf.readFromSync(r);
   return buf.bytes();
 }
 
 async function writeAll(w, arr) {
+  internals.warnOnDeprecatedApi(
+    "Deno.writeAll()",
+    new Error().stack,
+    "Use `writeAll()` from `https://deno.land/std/io/write_all.ts` instead.",
+  );
   let nwritten = 0;
   while (nwritten < arr.length) {
     nwritten += await w.write(TypedArrayPrototypeSubarray(arr, nwritten));
@@ -249,6 +269,11 @@ async function writeAll(w, arr) {
 }
 
 function writeAllSync(w, arr) {
+  internals.warnOnDeprecatedApi(
+    "Deno.writeAllSync()",
+    new Error().stack,
+    "Use `writeAllSync()` from `https://deno.land/std/io/write_all.ts` instead.",
+  );
   let nwritten = 0;
   while (nwritten < arr.length) {
     nwritten += w.writeSync(TypedArrayPrototypeSubarray(arr, nwritten));
diff --git a/runtime/js/40_fs_events.js b/runtime/js/40_fs_events.js
index 13cacc36b..0bc614335 100644
--- a/runtime/js/40_fs_events.js
+++ b/runtime/js/40_fs_events.js
@@ -1,6 +1,6 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
-import { core, primordials } from "ext:core/mod.js";
+import { core, internals, primordials } from "ext:core/mod.js";
 const {
   BadResourcePrototype,
   InterruptedPrototype,
@@ -49,6 +49,10 @@ class FsWatcher {
   // TODO(kt3k): This is deprecated. Will be removed in v2.0.
   // See https://github.com/denoland/deno/issues/10577 for details
   return(value) {
+    internals.warnOnDeprecatedApi(
+      "Deno.FsWatcher.return()",
+      new Error().stack,
+    );
     core.close(this.rid);
     return PromiseResolve({ value, done: true });
   }
diff --git a/runtime/js/90_deno_ns.js b/runtime/js/90_deno_ns.js
index 5bcc68a57..bba1f30d7 100644
--- a/runtime/js/90_deno_ns.js
+++ b/runtime/js/90_deno_ns.js
@@ -43,7 +43,10 @@ class FsFile extends fs.FsFile {
 }
 
 const denoNs = {
-  metrics: core.metrics,
+  metrics: () => {
+    internals.warnOnDeprecatedApi("Deno.metrics()", new Error().stack);
+    return core.metrics();
+  },
   Process: process.Process,
   run: process.run,
   isatty: tty.isatty,
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index 3fee1109b..7057f6d62 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -155,6 +155,7 @@ function warnOnDeprecatedApi(apiName, stack, ...suggestions) {
     "%c\u251c This API will be removed in Deno 2.0. Make sure to upgrade to a stable API before then.",
     "color: yellow;",
   );
+
   for (let i = 0; i < suggestions.length; i++) {
     const suggestion = suggestions[i];
     console.error("%c\u2502", "color: yellow;");