diff --git a/doc/api/util.md b/doc/api/util.md index ef11b744c5d..a4b9699c112 100644 --- a/doc/api/util.md +++ b/doc/api/util.md @@ -436,7 +436,7 @@ corresponding argument. Supported specifiers are: * `%s`: `String` will be used to convert all values except `BigInt`, `Object` and `-0`. `BigInt` values will be represented with an `n` and Objects that - have no user defined `toString` function are inspected using `util.inspect()` + have neither a user defined `toString` function nor `Symbol.toPrimitive` function are inspected using `util.inspect()` with options `{ depth: 0, colors: false, compact: 3 }`. * `%d`: `Number` will be used to convert all values except `BigInt` and `Symbol`. diff --git a/lib/internal/util/inspect.js b/lib/internal/util/inspect.js index f38eecba6ae..976d77fa43b 100644 --- a/lib/internal/util/inspect.js +++ b/lib/internal/util/inspect.js @@ -2161,27 +2161,32 @@ function hasBuiltInToString(value) { value = proxyTarget; } - // Check if value has a custom Symbol.toPrimitive transformation. - if (typeof value[SymbolToPrimitive] === 'function') { - return false; - } + let hasOwnToString = ObjectPrototypeHasOwnProperty; + let hasOwnToPrimitive = ObjectPrototypeHasOwnProperty; - // Count objects that have no `toString` function as built-in. + // Count objects without `toString` and `Symbol.toPrimitive` function as built-in. if (typeof value.toString !== 'function') { - return true; - } - - // The object has a own `toString` property. Thus it's not not a built-in one. - if (ObjectPrototypeHasOwnProperty(value, 'toString')) { + if (typeof value[SymbolToPrimitive] !== 'function') { + return true; + } else if (ObjectPrototypeHasOwnProperty(value, SymbolToPrimitive)) { + return false; + } + hasOwnToString = returnFalse; + } else if (ObjectPrototypeHasOwnProperty(value, 'toString')) { + return false; + } else if (typeof value[SymbolToPrimitive] !== 'function') { + hasOwnToPrimitive = returnFalse; + } else if (ObjectPrototypeHasOwnProperty(value, SymbolToPrimitive)) { return false; } - // Find the object that has the `toString` property as own property in the - // prototype chain. + // Find the object that has the `toString` property or `Symbol.toPrimitive` property + // as own property in the prototype chain. let pointer = value; do { pointer = ObjectGetPrototypeOf(pointer); - } while (!ObjectPrototypeHasOwnProperty(pointer, 'toString')); + } while (!hasOwnToString(pointer, 'toString') && + !hasOwnToPrimitive(pointer, SymbolToPrimitive)); // Check closer if the object is a built-in. const descriptor = ObjectGetOwnPropertyDescriptor(pointer, 'constructor'); @@ -2190,6 +2195,10 @@ function hasBuiltInToString(value) { builtInObjects.has(descriptor.value.name); } +function returnFalse() { + return false; +} + const firstErrorLine = (error) => StringPrototypeSplit(error.message, '\n', 1)[0]; let CIRCULAR_ERROR_MESSAGE; function tryStringify(arg) { diff --git a/test/parallel/test-util-format.js b/test/parallel/test-util-format.js index 6f222d0fea0..ad77c7cafd3 100644 --- a/test/parallel/test-util-format.js +++ b/test/parallel/test-util-format.js @@ -290,6 +290,68 @@ assert.strictEqual(util.format('%s', -Infinity), '-Infinity'); assert.strictEqual(util.format('%s', objectWithToPrimitive + ''), 'default context'); } +// built-in toPrimitive is the same behavior as inspect +{ + const date = new Date('2023-10-01T00:00:00Z'); + assert.strictEqual(util.format('%s', date), util.inspect(date)); + + const symbol = Symbol('foo'); + assert.strictEqual(util.format('%s', symbol), util.inspect(symbol)); +} + +// Prototype chain handling for toString +{ + function hasToStringButNoToPrimitive() {} + + hasToStringButNoToPrimitive.prototype.toString = function() { + return 'hasToStringButNoToPrimitive'; + }; + + let obj = new hasToStringButNoToPrimitive(); + assert.strictEqual(util.format('%s', obj.toString()), 'hasToStringButNoToPrimitive'); + + function inheritsFromHasToStringButNoToPrimitive() {} + Object.setPrototypeOf(inheritsFromHasToStringButNoToPrimitive.prototype, + hasToStringButNoToPrimitive.prototype); + obj = new inheritsFromHasToStringButNoToPrimitive(); + assert.strictEqual(util.format('%s', obj.toString()), 'hasToStringButNoToPrimitive'); +} + +// Prototype chain handling for Symbol.toPrimitive +{ + function hasToPrimitiveButNoToString() {} + + hasToPrimitiveButNoToString.prototype[Symbol.toPrimitive] = function() { + return 'hasToPrimitiveButNoToString'; + }; + + let obj = new hasToPrimitiveButNoToString(); + assert.strictEqual(util.format('%s', obj[Symbol.toPrimitive]()), 'hasToPrimitiveButNoToString'); + function inheritsFromHasToPrimitiveButNoToString() {} + Object.setPrototypeOf(inheritsFromHasToPrimitiveButNoToString.prototype, + hasToPrimitiveButNoToString.prototype); + obj = new inheritsFromHasToPrimitiveButNoToString(); + assert.strictEqual(util.format('%s', obj[Symbol.toPrimitive]()), 'hasToPrimitiveButNoToString'); +} + +// Prototype chain handling for both toString and Symbol.toPrimitive +{ + function hasBothToStringAndToPrimitive() {} + hasBothToStringAndToPrimitive.prototype.toString = function() { + return 'toString'; + }; + hasBothToStringAndToPrimitive.prototype[Symbol.toPrimitive] = function() { + return 'toPrimitive'; + }; + let obj = new hasBothToStringAndToPrimitive(); + assert.strictEqual(util.format('%s', obj.toString()), 'toString'); + function inheritsFromHasBothToStringAndToPrimitive() {} + Object.setPrototypeOf(inheritsFromHasBothToStringAndToPrimitive.prototype, + hasBothToStringAndToPrimitive.prototype); + obj = new inheritsFromHasBothToStringAndToPrimitive(); + assert.strictEqual(util.format('%s', obj.toString()), 'toString'); +} + // JSON format specifier assert.strictEqual(util.format('%j'), '%j'); assert.strictEqual(util.format('%j', 42), '42');