console: add color support

doc/api/console.md

@@ -60,9 +60,10 @@ changes:
   - version: v8.0.0
     pr-url: https://github.com/nodejs/node/pull/9744
     description: Errors that occur while writing to the underlying streams
-                 will now be ignored.
+                 will now be ignored by default.
 -->
 
+
 <!--type=class-->
 
 The `Console` class can be used to create a simple logger with configurable
@@ -77,9 +78,29 @@ const { Console } = require('console');
 const { Console } = console;
 ```
 
-### new Console(stdout[, stderr])
-* `stdout` {stream.Writable}
-* `stderr` {stream.Writable}
+### new Console(stdout[, stderr][, ignoreErrors])
+### new Console(options)
+<!-- YAML
+changes:
+  - version: v8.0.0
+    pr-url: https://github.com/nodejs/node/pull/9744
+    description: The `ignoreErrors` option was introduced.
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/19372
+    description: The `Console` constructor now supports an `options` argument,
+                 and the `colorMode` option was introduced.
+-->
+
+* `options` {Object}
+  * `stdout` {stream.Writable}
+  * `stderr` {stream.Writable}
+  * `ignoreErrors` {boolean} Ignore errors when writing to the underlying
+                             streams. **Default:** `true`.
+  * `colorMode` {boolean|string} Set color support for this `Console` instance.
+    Setting to `true` enables coloring while inspecting values, setting to
+    `'auto'` will make color support depend on the value of the `isTTY` property
+    and the value returned by `getColorDepth()` on the respective stream.
+    **Default:** `'auto'`
 
 Creates a new `Console` with one or two writable stream instances. `stdout` is a
 writable stream to print log or info output. `stderr` is used for warning or
@@ -89,7 +110,7 @@ error output. If `stderr` is not provided, `stdout` is used for `stderr`.
 const output = fs.createWriteStream('./stdout.log');
 const errorOutput = fs.createWriteStream('./stderr.log');
 // custom simple logger
-const logger = new Console(output, errorOutput);
+const logger = new Console({ stdout: output, stderr: errorOutput });
 // use it like console
 const count = 5;
 logger.log('count: %d', count);
@@ -100,7 +121,7 @@ The global `console` is a special `Console` whose output is sent to
 [`process.stdout`][] and [`process.stderr`][]. It is equivalent to calling:
 
 ```js
-new Console(process.stdout, process.stderr);
+new Console({ stdout: process.stdout, stderr: process.stderr });
 ```
 
 ### console.assert(value[, ...message])

doc/api/util.md

@@ -254,6 +254,24 @@ intended as a debugging tool. Some input values can have a significant
 performance overhead that can block the event loop. Use this function
 with care and never in a hot code path.
 
+## util.formatWithOptions(inspectOptions, format[, ...args])
+<!-- YAML
+added: REPLACEME
+-->
+
+* `inspectOptions` {Object}
+* `format` {string}
+
+This function is identical to [`util.format()`][], except in that it takes
+an `inspectOptions` argument which specifies options that are passed along to
+[`util.inspect()`][].
+
+```js
+util.formatWithOptions({ colors: true }, 'See object %O', { foo: 42 });
+// Returns 'See object { foo: 42 }', where `42` is colored as a number
+// when printed to a terminal.
+```
+
 ## util.getSystemErrorName(err)
 <!-- YAML
 added: v9.7.0
@@ -2054,6 +2072,7 @@ Deprecated predecessor of `console.log`.
 [`Set`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set
 [`SharedArrayBuffer`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer
 [`TypedArray`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
+[`util.format()`]: #util_util_format_format_args
 [`util.inspect()`]: #util_util_inspect_object_options
 [`util.promisify()`]: #util_util_promisify_original
 [`util.types.isAnyArrayBuffer()`]: #util_util_types_isanyarraybuffer_value

lib/console.js

@@ -26,6 +26,7 @@ const {
   codes: {
     ERR_CONSOLE_WRITABLE_STREAM,
     ERR_INVALID_ARG_TYPE,
+    ERR_INVALID_ARG_VALUE,
   },
 } = require('internal/errors');
 const { previewMapIterator, previewSetIterator } = require('internal/v8');
@@ -49,18 +50,38 @@ const {
 } = Array;
 
 // Track amount of indentation required via `console.group()`.
-const kGroupIndent = Symbol('groupIndent');
+const kGroupIndent = Symbol('kGroupIndent');
 
-function Console(stdout, stderr, ignoreErrors = true) {
+const kFormatForStderr = Symbol('kFormatForStderr');
+const kFormatForStdout = Symbol('kFormatForStdout');
+const kGetInspectOptions = Symbol('kGetInspectOptions');
+const kColorMode = Symbol('kColorMode');
+
+function Console(options /* or: stdout, stderr, ignoreErrors = true */) {
   if (!(this instanceof Console)) {
-    return new Console(stdout, stderr, ignoreErrors);
+    return new Console(...arguments);
+  }
+
+  let stdout, stderr, ignoreErrors, colorMode;
+  if (options && typeof options.write !== 'function') {
+    ({
+      stdout,
+      stderr = stdout,
+      ignoreErrors = true,
+      colorMode = 'auto'
+    } = options);
+  } else {
+    return new Console({
+      stdout: options,
+      stderr: arguments[1],
+      ignoreErrors: arguments[2]
+    });
   }
+
   if (!stdout || typeof stdout.write !== 'function') {
     throw new ERR_CONSOLE_WRITABLE_STREAM('stdout');
   }
-  if (!stderr) {
-    stderr = stdout;
-  } else if (typeof stderr.write !== 'function') {
+  if (!stderr || typeof stderr.write !== 'function') {
     throw new ERR_CONSOLE_WRITABLE_STREAM('stderr');
   }
 
@@ -82,7 +103,11 @@ function Console(stdout, stderr, ignoreErrors = true) {
   prop.value = createWriteErrorHandler(stderr);
   Object.defineProperty(this, '_stderrErrorHandler', prop);
 
+  if (typeof colorMode !== 'boolean' && colorMode !== 'auto')
+    throw new ERR_INVALID_ARG_VALUE('colorMode', colorMode);
+
   this[kCounts] = new Map();
+  this[kColorMode] = colorMode;
 
   Object.defineProperty(this, kGroupIndent, { writable: true });
   this[kGroupIndent] = '';
@@ -144,13 +169,33 @@ function write(ignoreErrors, stream, string, errorhandler, groupIndent) {
   }
 }
 
+const kColorInspectOptions = { colors: true };
+const kNoColorInspectOptions = {};
+Console.prototype[kGetInspectOptions] = function(stream) {
+  let color = this[kColorMode];
+  if (color === 'auto') {
+    color = stream.isTTY && (
+      typeof stream.getColorDepth === 'function' ?
+        stream.getColorDepth() > 2 : true);
+  }
+
+  return color ? kColorInspectOptions : kNoColorInspectOptions;
+};
+
+Console.prototype[kFormatForStdout] = function(args) {
+  const opts = this[kGetInspectOptions](this._stdout);
+  return util.formatWithOptions(opts, ...args);
+};
+
+Console.prototype[kFormatForStderr] = function(args) {
+  const opts = this[kGetInspectOptions](this._stderr);
+  return util.formatWithOptions(opts, ...args);
+};
+
 Console.prototype.log = function log(...args) {
   write(this._ignoreErrors,
         this._stdout,
-        // The performance of .apply and the spread operator seems on par in V8
-        // 6.3 but the spread operator, unlike .apply(), pushes the elements
-        // onto the stack. That is, it makes stack overflows more likely.
-        util.format.apply(null, args),
+        this[kFormatForStdout](args),
         this._stdoutErrorHandler,
         this[kGroupIndent]);
 };
@@ -161,14 +206,16 @@ Console.prototype.dirxml = Console.prototype.log;
 Console.prototype.warn = function warn(...args) {
   write(this._ignoreErrors,
         this._stderr,
-        util.format.apply(null, args),
+        this[kFormatForStderr](args),
         this._stderrErrorHandler,
         this[kGroupIndent]);
 };
 Console.prototype.error = Console.prototype.warn;
 
 Console.prototype.dir = function dir(object, options) {
-  options = Object.assign({ customInspect: false }, options);
+  options = Object.assign({
+    customInspect: false
+  }, this[kGetInspectOptions](this._stdout), options);
   write(this._ignoreErrors,
         this._stdout,
         util.inspect(object, options),
@@ -199,7 +246,7 @@ Console.prototype.timeEnd = function timeEnd(label = 'default') {
 Console.prototype.trace = function trace(...args) {
   const err = {
     name: 'Trace',
-    message: util.format.apply(null, args)
+    message: this[kFormatForStderr](args)
   };
   Error.captureStackTrace(err, trace);
   this.error(err.stack);
@@ -208,7 +255,7 @@ Console.prototype.trace = function trace(...args) {
 Console.prototype.assert = function assert(expression, ...args) {
   if (!expression) {
     args[0] = `Assertion failed${args.length === 0 ? '' : `: ${args[0]}`}`;
-    this.warn(util.format.apply(null, args));
+    this.warn(this[kFormatForStderr](args));
   }
 };
 
@@ -369,7 +416,10 @@ Console.prototype.table = function(tabularData, properties) {
   return final(keys, values);
 };
 
-module.exports = new Console(process.stdout, process.stderr);
+module.exports = new Console({
+  stdout: process.stdout,
+  stderr: process.stderr
+});
 module.exports.Console = Console;
 
 function noop() {}

lib/util.js

@@ -173,23 +173,28 @@ function tryStringify(arg) {
   }
 }
 
-function format(f) {
+const emptyOptions = {};
+function format(...args) {
+  return formatWithOptions(emptyOptions, ...args);
+}
+
+function formatWithOptions(inspectOptions, f) {
   let i, tempStr;
   if (typeof f !== 'string') {
-    if (arguments.length === 0) return '';
+    if (arguments.length === 1) return '';
     let res = '';
-    for (i = 0; i < arguments.length - 1; i++) {
-      res += inspect(arguments[i]);
+    for (i = 1; i < arguments.length - 1; i++) {
+      res += inspect(arguments[i], inspectOptions);
       res += ' ';
     }
-    res += inspect(arguments[i]);
+    res += inspect(arguments[i], inspectOptions);
     return res;
   }
 
-  if (arguments.length === 1) return f;
+  if (arguments.length === 2) return f;
 
   let str = '';
-  let a = 1;
+  let a = 2;
   let lastPos = 0;
   for (i = 0; i < f.length - 1; i++) {
     if (f.charCodeAt(i) === 37) { // '%'
@@ -206,12 +211,17 @@ function format(f) {
             tempStr = `${Number(arguments[a++])}`;
             break;
           case 79: // 'O'
-            tempStr = inspect(arguments[a++]);
+            tempStr = inspect(arguments[a++], inspectOptions);
             break;
           case 111: // 'o'
-            tempStr = inspect(arguments[a++],
-                              { showHidden: true, showProxy: true });
+          {
+            const opts = Object.assign({}, inspectOptions, {
+              showHidden: true,
+              showProxy: true
+            });
+            tempStr = inspect(arguments[a++], opts);
             break;
+          }
           case 105: // 'i'
             tempStr = `${parseInt(arguments[a++])}`;
             break;
@@ -244,7 +254,7 @@ function format(f) {
     if ((typeof x !== 'object' && typeof x !== 'symbol') || x === null) {
       str += ` ${x}`;
     } else {
-      str += ` ${inspect(x)}`;
+      str += ` ${inspect(x, inspectOptions)}`;
     }
   }
   return str;
@@ -1206,6 +1216,7 @@ module.exports = exports = {
   debuglog,
   deprecate,
   format,
+  formatWithOptions,
   getSystemErrorName,
   inherits,
   inspect,

test/parallel/test-console-tty-colors.js

@@ -0,0 +1,46 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const util = require('util');
+const { Writable } = require('stream');
+const { Console } = require('console');
+
+function check(isTTY, colorMode, expectedColorMode) {
+  const items = [
+    1,
+    { a: 2 },
+    [ 'foo' ],
+    { '\\a': '\\bar' }
+  ];
+
+  let i = 0;
+  const stream = new Writable({
+    write: common.mustCall((chunk, enc, cb) => {
+      assert.strictEqual(chunk.trim(),
+                         util.inspect(items[i++], {
+                           colors: expectedColorMode
+                         }));
+      cb();
+    }, items.length),
+    decodeStrings: false
+  });
+  stream.isTTY = isTTY;
+
+  // Set ignoreErrors to `false` here so that we see assertion failures
+  // from the `write()` call happen.
+  const testConsole = new Console({
+    stdout: stream,
+    ignoreErrors: false,
+    colorMode
+  });
+  for (const item of items) {
+    testConsole.log(item);
+  }
+}
+
+check(true, 'auto', true);
+check(false, 'auto', false);
+check(true, true, true);
+check(false, true, true);
+check(true, false, false);
+check(false, false, false);

test/parallel/test-console.js

@@ -51,9 +51,11 @@ const custom_inspect = { foo: 'bar', inspect: () => 'inspect' };
 
 const strings = [];
 const errStrings = [];
+process.stdout.isTTY = false;
 common.hijackStdout(function(data) {
   strings.push(data);
 });
+process.stderr.isTTY = false;
 common.hijackStderr(function(data) {
   errStrings.push(data);
 });

test/pseudo-tty/console_colors.js

@@ -0,0 +1,9 @@
+'use strict';
+require('../common');
+// Make this test OS-independent by overriding stdio getColorDepth().
+process.stdout.getColorDepth = () => 8;
+process.stderr.getColorDepth = () => 8;
+
+console.log({ foo: 'bar' });
+console.log('%s q', 'string');
+console.log('%o with object format param', { foo: 'bar' });

test/pseudo-tty/console_colors.out

@@ -0,0 +1,3 @@
+{ foo: *[32m'bar'*[39m }
+string q
+{ foo: *[32m'bar'*[39m } with object format param