feat: Deno.{stdin,stdout,stderr}.isTerminal(), deprecate Deno.isatty() (#22011)

This change:
1. Implements `Deno.stdin.isTerminal()`, `Deno.stdout.isTerminal()` and
`Deno.stderr.isTerminal()`.
2. Deprecates `Deno.isatty()` for removal in Deno v2, in favour of the
above instance methods.
3. Replaces use of `Deno.isatty()` with the above instance methods.

Related #21995

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
Co-authored-by: Divy Srivastava <dj.srivastava23@gmail.com>

cli/tests/unit/tty_test.ts

@@ -4,7 +4,7 @@ import { assert } from "./test_util.ts";
 // Note tests for Deno.stdin.setRaw is in integration tests.
 
 Deno.test(function consoleSize() {
-  if (!Deno.isatty(Deno.stdout.rid)) {
+  if (!Deno.stdout.isTerminal()) {
     return;
   }
   const result = Deno.consoleSize();

cli/tests/unit_node/process_test.ts

@@ -356,14 +356,14 @@ Deno.test({
   name: "process.stdin",
   fn() {
     assertEquals(process.stdin.fd, Deno.stdin.rid);
-    assertEquals(process.stdin.isTTY, Deno.isatty(Deno.stdin.rid));
+    assertEquals(process.stdin.isTTY, Deno.stdin.isTerminal());
   },
 });
 
 Deno.test({
   name: "process.stdin readable with a TTY",
   // TODO(PolarETech): Run this test even in non tty environment
-  ignore: !Deno.isatty(Deno.stdin.rid),
+  ignore: !Deno.stdin.isTerminal(),
   // stdin resource is present before the test starts.
   sanitizeResources: false,
   async fn() {
@@ -535,7 +535,7 @@ Deno.test({
   name: "process.stdout",
   fn() {
     assertEquals(process.stdout.fd, Deno.stdout.rid);
-    const isTTY = Deno.isatty(Deno.stdout.rid);
+    const isTTY = Deno.stdout.isTerminal();
     assertEquals(process.stdout.isTTY, isTTY);
     const consoleSize = isTTY ? Deno.consoleSize() : undefined;
     assertEquals(process.stdout.columns, consoleSize?.columns);
@@ -563,7 +563,7 @@ Deno.test({
   name: "process.stderr",
   fn() {
     assertEquals(process.stderr.fd, Deno.stderr.rid);
-    const isTTY = Deno.isatty(Deno.stderr.rid);
+    const isTTY = Deno.stderr.isTerminal();
     assertEquals(process.stderr.isTTY, isTTY);
     const consoleSize = isTTY ? Deno.consoleSize() : undefined;
     assertEquals(process.stderr.columns, consoleSize?.columns);

cli/tests/unit_node/tty_test.ts

@@ -6,9 +6,9 @@ import { isatty } from "node:tty";
 import process from "node:process";
 
 Deno.test("[node/tty isatty] returns true when fd is a tty, false otherwise", () => {
-  assert(Deno.isatty(Deno.stdin.rid) === isatty(Deno.stdin.rid));
-  assert(Deno.isatty(Deno.stdout.rid) === isatty(Deno.stdout.rid));
-  assert(Deno.isatty(Deno.stderr.rid) === isatty(Deno.stderr.rid));
+  assert(Deno.stdin.isTerminal() === isatty(Deno.stdin.rid));
+  assert(Deno.stdout.isTerminal() === isatty(Deno.stdout.rid));
+  assert(Deno.stderr.isTerminal() === isatty(Deno.stderr.rid));
 
   const file = Deno.openSync("README.md");
   assert(!isatty(file.rid));
@@ -32,6 +32,6 @@ Deno.test("[node/tty isatty] returns false for irrelevant values", () => {
 });
 
 Deno.test("[node/tty WriteStream.isTTY] returns true when fd is a tty", () => {
-  assert(Deno.isatty(Deno.stdin.rid) === process.stdin.isTTY);
-  assert(Deno.isatty(Deno.stdout.rid) === process.stdout.isTTY);
+  assert(Deno.stdin.isTerminal() === process.stdin.isTTY);
+  assert(Deno.stdout.isTerminal() === process.stdout.isTTY);
 });

cli/tsc/dts/lib.deno.ns.d.ts

@@ -2612,6 +2612,17 @@ declare namespace Deno {
      * @category I/O
      */
     setRaw(mode: boolean, options?: SetRawOptions): void;
+    /**
+     * Checks if `stdin` is a TTY (terminal).
+     *
+     * ```ts
+     * // This example is system and context specific
+     * Deno.stdin.isTerminal(); // true
+     * ```
+     *
+     * @category I/O
+     */
+    isTerminal(): boolean;
   };
   /** A reference to `stdout` which can be used to write directly to `stdout`.
    * It implements the Deno specific {@linkcode Writer}, {@linkcode WriterSync},
@@ -2629,6 +2640,17 @@ declare namespace Deno {
     readonly rid: number;
     /** A writable stream interface to `stdout`. */
     readonly writable: WritableStream<Uint8Array>;
+    /**
+     * Checks if `stdout` is a TTY (terminal).
+     *
+     * ```ts
+     * // This example is system and context specific
+     * Deno.stdout.isTerminal(); // true
+     * ```
+     *
+     * @category I/O
+     */
+    isTerminal(): boolean;
   };
   /** A reference to `stderr` which can be used to write directly to `stderr`.
    * It implements the Deno specific {@linkcode Writer}, {@linkcode WriterSync},
@@ -2646,6 +2668,17 @@ declare namespace Deno {
     readonly rid: number;
     /** A writable stream interface to `stderr`. */
     readonly writable: WritableStream<Uint8Array>;
+    /**
+     * Checks if `stderr` is a TTY (terminal).
+     *
+     * ```ts
+     * // This example is system and context specific
+     * Deno.stderr.isTerminal(); // true
+     * ```
+     *
+     * @category I/O
+     */
+    isTerminal(): boolean;
   };
 
   /**
@@ -2728,6 +2761,10 @@ declare namespace Deno {
    * Deno.close(ttyRid);
    * ```
    *
+   * @deprecated Use `Deno.stdin.isTerminal()`, `Deno.stdout.isTerminal()` or
+   * `Deno.stderr.isTerminal()` instead.
+   * {@linkcode Deno.isatty} will be removed in v2.0.0.
+   *
    * @category I/O
    */
   export function isatty(rid: number): boolean;

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();

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;

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) {

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;
   }

runtime/js/40_tty.js

@@ -1,9 +1,9 @@
 // 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 {
   op_console_size,
-  op_isatty,
-} = core.ensureFastOps();
+  op_is_terminal,
+} = core.ensureFastOps(true);
 const {
   Uint32Array,
 } = primordials;
@@ -16,7 +16,12 @@ function consoleSize() {
 }
 
 function isatty(rid) {
-  return op_isatty(rid);
+  internals.warnOnDeprecatedApi(
+    "Deno.isatty()",
+    new Error().stack,
+    "Use `stdStream.isTerminal()` instead.",
+  );
+  return op_is_terminal(rid);
 }
 
 export { consoleSize, isatty };

runtime/js/41_prompt.js

@@ -9,14 +9,13 @@ const {
   Uint8Array,
 } = primordials;
 
-import { isatty } from "ext:runtime/40_tty.js";
 import { stdin } from "ext:deno_io/12_io.js";
 
 const LF = StringPrototypeCharCodeAt("\n", 0);
 const CR = StringPrototypeCharCodeAt("\r", 0);
 
 function alert(message = "Alert") {
-  if (!isatty(stdin.rid)) {
+  if (!stdin.isTerminal()) {
     return;
   }
 
@@ -26,7 +25,7 @@ function alert(message = "Alert") {
 }
 
 function confirm(message = "Confirm") {
-  if (!isatty(stdin.rid)) {
+  if (!stdin.isTerminal()) {
     return false;
   }
 
@@ -40,7 +39,7 @@ function confirm(message = "Confirm") {
 function prompt(message = "Prompt", defaultValue) {
   defaultValue ??= "";
 
-  if (!isatty(stdin.rid)) {
+  if (!stdin.isTerminal()) {
     return null;
   }
 

runtime/ops/tty.rs

@@ -52,7 +52,7 @@ deno_core::extension!(
   deno_tty,
   ops = [
     op_stdin_set_raw,
-    op_isatty,
+    op_is_terminal,
     op_console_size,
     op_read_line_prompt
   ],
@@ -210,7 +210,7 @@ fn op_stdin_set_raw(
 }
 
 #[op2(fast)]
-fn op_isatty(state: &mut OpState, rid: u32) -> Result<bool, AnyError> {
+fn op_is_terminal(state: &mut OpState, rid: u32) -> Result<bool, AnyError> {
   let handle = state.resource_table.get_handle(rid)?;
   Ok(handle.is_terminal())
 }