4 files changed, 31 insertions, 13 deletions

diff --git a/ext/io/12_io.js b/ext/io/12_io.js
index d9b91a947..9f4a3766b 100644
--- a/ext/io/12_io.js
+++ b/ext/io/12_io.js
@@ -7,6 +7,7 @@
 import { core, primordials } from "ext:core/mod.js";
 const {
   op_stdin_set_raw,
+  op_is_terminal,
 } = core.ensureFastOps(true);
 const {
   Uint8Array,
@@ -197,6 +198,10 @@ class Stdin {
     const cbreak = !!(options.cbreak ?? false);
     op_stdin_set_raw(mode, cbreak);
   }
+
+  isTerminal() {
+    return op_is_terminal(this.rid);
+  }
 }
 
 class Stdout {
@@ -227,6 +232,10 @@ class Stdout {
     }
     return this.#writable;
   }
+
+  isTerminal() {
+    return op_is_terminal(this.rid);
+  }
 }
 
 class Stderr {
@@ -257,6 +266,10 @@ class Stderr {
     }
     return this.#writable;
   }
+
+  isTerminal() {
+    return op_is_terminal(this.rid);
+  }
 }
 
 const stdin = new Stdin();
diff --git a/ext/node/polyfills/_process/streams.mjs b/ext/node/polyfills/_process/streams.mjs
index 14d58fcab..166d099c8 100644
--- a/ext/node/polyfills/_process/streams.mjs
+++ b/ext/node/polyfills/_process/streams.mjs
@@ -46,30 +46,27 @@ export function createWritableStdioStream(writer, name) {
       enumerable: true,
       configurable: true,
       get: () =>
-        Deno.isatty?.(writer?.rid) ? Deno.consoleSize?.().columns : undefined,
+        writer?.isTerminal() ? Deno.consoleSize?.().columns : undefined,
     },
     rows: {
       enumerable: true,
       configurable: true,
-      get: () =>
-        Deno.isatty?.(writer?.rid) ? Deno.consoleSize?.().rows : undefined,
+      get: () => writer?.isTerminal() ? Deno.consoleSize?.().rows : undefined,
     },
     isTTY: {
       enumerable: true,
       configurable: true,
-      get: () => Deno.isatty?.(writer?.rid),
+      get: () => writer?.isTerminal(),
     },
     getWindowSize: {
       enumerable: true,
       configurable: true,
       value: () =>
-        Deno.isatty?.(writer?.rid)
-          ? Object.values(Deno.consoleSize?.())
-          : undefined,
+        writer?.isTerminal() ? Object.values(Deno.consoleSize?.()) : undefined,
     },
   });
 
-  if (Deno.isatty?.(writer?.rid)) {
+  if (writer?.isTerminal()) {
     // These belong on tty.WriteStream(), but the TTY streams currently have
     // following problems:
     // 1. Using them here introduces a circular dependency.
@@ -180,7 +177,7 @@ export const initStdin = () => {
     enumerable: true,
     configurable: true,
     get() {
-      return Deno.isatty?.(io.stdin.rid);
+      return io.stdin.isTerminal();
     },
   });
   stdin._isRawMode = false;
diff --git a/ext/node/polyfills/assertion_error.ts b/ext/node/polyfills/assertion_error.ts
index bec1f6ba5..ff1168dc3 100644
--- a/ext/node/polyfills/assertion_error.ts
+++ b/ext/node/polyfills/assertion_error.ts
@@ -163,7 +163,7 @@ export function createErrDiff(
       // If the stderr is a tty and the input length is lower than the current
       // columns per line, add a mismatch indicator below the output. If it is
       // not a tty, use a default value of 80 characters.
-      const maxLength = Deno.isatty(io.stderr.rid) ? getConsoleWidth() : 80;
+      const maxLength = io.stderr.isTerminal() ? getConsoleWidth() : 80;
       if (inputLength < maxLength) {
         while (actualRaw[i] === expectedRaw[i]) {
           i++;
@@ -406,7 +406,7 @@ export class AssertionError extends Error {
     if (message != null) {
       super(String(message));
     } else {
-      if (Deno.isatty(io.stderr.rid)) {
+      if (io.stderr.isTerminal()) {
         // Reset on each call to make sure we handle dynamically set environment
         // variables correct.
         if (Deno.noColor) {
diff --git a/ext/node/polyfills/tty.js b/ext/node/polyfills/tty.js
index 86fd34d7c..eae1db2d9 100644
--- a/ext/node/polyfills/tty.js
+++ b/ext/node/polyfills/tty.js
@@ -1,9 +1,12 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
-import { primordials } from "ext:core/mod.js";
+import { core, primordials } from "ext:core/mod.js";
 const {
   Error,
 } = primordials;
+const {
+  op_is_terminal,
+} = core.ensureFastOps(true);
 
 import { ERR_INVALID_FD } from "ext:deno_node/internal/errors.ts";
 import { LibuvStreamWrap } from "ext:deno_node/internal_binding/stream_wrap.ts";
@@ -17,7 +20,12 @@ function isatty(fd) {
     return false;
   }
   try {
-    return Deno.isatty(fd);
+    /**
+     * TODO: Treat `fd` as real file descriptors. Currently, `rid` 0, 1, 2
+     * correspond to `fd` 0, 1, 2 (stdin, stdout, stderr). This may change in
+     * the future.
+     */
+    return op_is_terminal(fd);
   } catch (_) {
     return false;
   }