Lines Matching refs:util
7 <!-- source_link=lib/util.js -->
9 The `util` module supports the needs of Node.js internal APIs. Many of the
14 const util = require('util');
17 ## `util.callbackify(original)`
32 const util = require('util');
37 const callbackFunction = util.callbackify(fn);
64 const callbackFunction = util.callbackify(fn);
73 ## `util.debuglog(section[, callback])`
84 The `util.debuglog()` method is used to create a function that conditionally
91 const util = require('util');
92 const debuglog = util.debuglog('foo');
110 const util = require('util');
111 const debuglog = util.debuglog('foo-bar');
131 const util = require('util');
132 let debuglog = util.debuglog('internals', (debug) => {
146 The `util.debuglog().enabled` getter is used to create a test that can be used
153 const util = require('util');
154 const enabled = util.debuglog('foo').enabled;
167 ## `util.debug(section)`
172 Alias for `util.debuglog`. Usage allows for readability of that doesn't imply
173 logging when only using `util.debuglog().enabled`.
175 ## `util.deprecate(fn, msg[, code])`
191 The `util.deprecate()` method wraps `fn` (which may be a function or class) in
195 const util = require('util');
197 exports.obsoleteFunction = util.deprecate(() => {
202 When called, `util.deprecate()` will return a function that will emit a
208 If the same optional `code` is supplied in multiple calls to `util.deprecate()`,
212 const util = require('util');
214 const fn1 = util.deprecate(someFunction, someMessage, 'DEP0001');
215 const fn2 = util.deprecate(someOtherFunction, someOtherMessage, 'DEP0001');
222 the first deprecation warning, the `util.deprecate()` method does nothing.
237 ## `util.format(format[, ...args])`
276 The `util.format()` method returns a formatted string using the first argument
283 have no user defined `toString` function are inspected using `util.inspect()`
293 object formatting. Similar to `util.inspect()` with options
297 object formatting. Similar to `util.inspect()` without options. This will show
306 util.format('%s:%s', 'foo');
311 `util.inspect()` if their type is not `string`.
313 If there are more arguments passed to the `util.format()` method than the
318 util.format('%s:%s', 'foo', 'bar', 'baz');
322 If the first argument does not contain a valid format specifier, `util.format()`
326 util.format(1, 2, 3);
330 If only one argument is passed to `util.format()`, it is returned as it is
334 util.format('%% %s');
338 `util.format()` is a synchronous method that is intended as a debugging tool.
342 ## `util.formatWithOptions(inspectOptions, format[, ...args])`
350 This function is identical to [`util.format()`][], except in that it takes
352 [`util.inspect()`][].
355 util.formatWithOptions({ colors: true }, 'See object %O', { foo: 42 });
360 ## `util.getSystemErrorName(err)`
374 const name = util.getSystemErrorName(err.errno);
379 ## `util.getSystemErrorMap()`
392 const errorMap = util.getSystemErrorMap();
398 ## `util.inherits(constructor, superConstructor)`
412 Usage of `util.inherits()` is discouraged. Please use the ES6 `class` and
426 const util = require('util');
433 util.inherits(MyStream, EventEmitter);
469 ## `util.inspect(object[, options])`
470 ## `util.inspect(object[, showHidden[, depth[, colors]]])`
562 codes. Colors are customizable. See [Customizing `util.inspect` colors][].
565 `[util.inspect.custom](depth, opts)` functions are not invoked.
598 The `util.inspect()` method returns a string representation of `object` that is
599 intended for debugging. The output of `util.inspect` may change at any time
602 `util.inspect()` will use the constructor's name and/or `@@toStringTag` to make
616 util.inspect(new Foo()); // 'Foo [bar] {}'
617 util.inspect(new Bar()); // 'Bar {}'
618 util.inspect(baz); // '[foo] {}'
624 const { inspect } = require('util');
639 The following example inspects all properties of the `util` object:
642 const util = require('util');
644 console.log(util.inspect(util, { showHidden: true, depth: null }));
650 const util = require('util');
660 console.log(util.inspect(o, { compact: true, depth: 5, breakLength: 80 }));
672 console.log(util.inspect(o, { compact: false, depth: 5, breakLength: 80 }));
709 const { inspect } = require('util');
720 impact the result of `util.inspect()`.
723 const { inspect } = require('util');
747 `util.inspect()` is a synchronous method intended for debugging. Its maximum
751 ### Customizing `util.inspect` colors
755 Color output (if enabled) of `util.inspect` is customizable globally
756 via the `util.inspect.styles` and `util.inspect.colors` properties.
758 `util.inspect.styles` is a map associating a style name to a color from
759 `util.inspect.colors`.
847 [`[util.inspect.custom](depth, opts)`][util.inspect.custom] function,
848 which `util.inspect()` will invoke and use the result of when inspecting
852 const util = require('util');
859 [util.inspect.custom](depth, options) {
870 const inner = util.inspect(this.value, newOptions)
878 util.inspect(box);
882 Custom `[util.inspect.custom](depth, opts)` functions typically return a string
884 `util.inspect()`.
887 const util = require('util');
890 obj[util.inspect.custom] = (depth) => {
894 util.inspect(obj);
898 ### `util.inspect.custom`
909 In addition to being accessible through `util.inspect.custom`, this
911 accessed in any environment as `Symbol.for('nodejs.util.inspect.custom')`.
914 const inspect = Symbol.for('nodejs.util.inspect.custom');
937 ### `util.inspect.defaultOptions`
943 `util.inspect`. This is useful for functions like `console.log` or
944 `util.format` which implicitly call into `util.inspect`. It shall be set to an
945 object containing one or more valid [`util.inspect()`][] options. Setting
949 const util = require('util');
953 util.inspect.defaultOptions.maxArrayLength = null;
957 ## `util.isDeepStrictEqual(val1, val2)`
972 ## `util.promisify(original)`
985 const util = require('util');
988 const stat = util.promisify(fs.stat);
999 const util = require('util');
1002 const stat = util.promisify(fs.stat);
1010 If there is an `original[util.promisify.custom]` property present, `promisify`
1023 const util = require('util');
1037 const naiveBar = util.promisify(foo.bar);
1049 Using the `util.promisify.custom` symbol one can override the return value of
1050 [`util.promisify()`][]:
1053 const util = require('util');
1059 doSomething[util.promisify.custom] = (foo) => {
1063 const promisified = util.promisify(doSomething);
1064 console.log(promisified === doSomething[util.promisify.custom]);
1075 doSomething[util.promisify.custom] = (foo) => {
1085 ### `util.promisify.custom`
1099 In addition to being accessible through `util.promisify.custom`, this
1101 accessed in any environment as `Symbol.for('nodejs.util.promisify.custom')`.
1107 const kCustomPromisifiedSymbol = Symbol.for('nodejs.util.promisify.custom');
1116 ## Class: `util.TextDecoder`
1260 ## Class: `util.TextEncoder`
1311 ## `util.toUSVString(string)`
1322 ## `util.types`
1327 `util.types` provides type checks for different kinds of built-in objects.
1336 ### `util.types.isAnyArrayBuffer(value)`
1347 See also [`util.types.isArrayBuffer()`][] and
1348 [`util.types.isSharedArrayBuffer()`][].
1351 util.types.isAnyArrayBuffer(new ArrayBuffer()); // Returns true
1352 util.types.isAnyArrayBuffer(new SharedArrayBuffer()); // Returns true
1355 ### `util.types.isArrayBufferView(value)`
1368 util.types.isArrayBufferView(new Int8Array()); // true
1369 util.types.isArrayBufferView(Buffer.from('hello world')); // true
1370 util.types.isArrayBufferView(new DataView(new ArrayBuffer(16))); // true
1371 util.types.isArrayBufferView(new ArrayBuffer()); // false
1374 ### `util.types.isArgumentsObject(value)`
1387 util.types.isArgumentsObject(arguments); // Returns true
1391 ### `util.types.isArrayBuffer(value)`
1401 desirable to test for both; See [`util.types.isAnyArrayBuffer()`][] for that.
1404 util.types.isArrayBuffer(new ArrayBuffer()); // Returns true
1405 util.types.isArrayBuffer(new SharedArrayBuffer()); // Returns false
1408 ### `util.types.isAsyncFunction(value)`
1422 util.types.isAsyncFunction(function foo() {}); // Returns false
1423 util.types.isAsyncFunction(async function foo() {}); // Returns true
1426 ### `util.types.isBigInt64Array(value)`
1437 util.types.isBigInt64Array(new BigInt64Array()); // Returns true
1438 util.types.isBigInt64Array(new BigUint64Array()); // Returns false
1441 ### `util.types.isBigUint64Array(value)`
1452 util.types.isBigUint64Array(new BigInt64Array()); // Returns false
1453 util.types.isBigUint64Array(new BigUint64Array()); // Returns true
1456 ### `util.types.isBooleanObject(value)`
1468 util.types.isBooleanObject(false); // Returns false
1469 util.types.isBooleanObject(true); // Returns false
1470 util.types.isBooleanObject(new Boolean(false)); // Returns true
1471 util.types.isBooleanObject(new Boolean(true)); // Returns true
1472 util.types.isBooleanObject(Boolean(false)); // Returns false
1473 util.types.isBooleanObject(Boolean(true)); // Returns false
1476 ### `util.types.isBoxedPrimitive(value)`
1490 util.types.isBoxedPrimitive(false); // Returns false
1491 util.types.isBoxedPrimitive(new Boolean(false)); // Returns true
1492 util.types.isBoxedPrimitive(Symbol('foo')); // Returns false
1493 util.types.isBoxedPrimitive(Object(Symbol('foo'))); // Returns true
1494 util.types.isBoxedPrimitive(Object(BigInt(5))); // Returns true
1497 ### `util.types.isDataView(value)`
1509 util.types.isDataView(new DataView(ab)); // Returns true
1510 util.types.isDataView(new Float64Array()); // Returns false
1515 ### `util.types.isDate(value)`
1526 util.types.isDate(new Date()); // Returns true
1529 ### `util.types.isExternal(value)`
1566 util.types.isExternal(data); // returns true
1567 util.types.isExternal(0); // returns false
1568 util.types.isExternal(new String('foo')); // returns false
1574 ### `util.types.isFloat32Array(value)`
1585 util.types.isFloat32Array(new ArrayBuffer()); // Returns false
1586 util.types.isFloat32Array(new Float32Array()); // Returns true
1587 util.types.isFloat32Array(new Float64Array()); // Returns false
1590 ### `util.types.isFloat64Array(value)`
1601 util.types.isFloat64Array(new ArrayBuffer()); // Returns false
1602 util.types.isFloat64Array(new Uint8Array()); // Returns false
1603 util.types.isFloat64Array(new Float64Array()); // Returns true
1606 ### `util.types.isGeneratorFunction(value)`
1620 util.types.isGeneratorFunction(function foo() {}); // Returns false
1621 util.types.isGeneratorFunction(function* foo() {}); // Returns true
1624 ### `util.types.isGeneratorObject(value)`
1641 util.types.isGeneratorObject(generator); // Returns true
1644 ### `util.types.isInt8Array(value)`
1655 util.types.isInt8Array(new ArrayBuffer()); // Returns false
1656 util.types.isInt8Array(new Int8Array()); // Returns true
1657 util.types.isInt8Array(new Float64Array()); // Returns false
1660 ### `util.types.isInt16Array(value)`
1671 util.types.isInt16Array(new ArrayBuffer()); // Returns false
1672 util.types.isInt16Array(new Int16Array()); // Returns true
1673 util.types.isInt16Array(new Float64Array()); // Returns false
1676 ### `util.types.isInt32Array(value)`
1687 util.types.isInt32Array(new ArrayBuffer()); // Returns false
1688 util.types.isInt32Array(new Int32Array()); // Returns true
1689 util.types.isInt32Array(new Float64Array()); // Returns false
1692 ### `util.types.isMap(value)`
1703 util.types.isMap(new Map()); // Returns true
1706 ### `util.types.isMapIterator(value)`
1719 util.types.isMapIterator(map.keys()); // Returns true
1720 util.types.isMapIterator(map.values()); // Returns true
1721 util.types.isMapIterator(map.entries()); // Returns true
1722 util.types.isMapIterator(map[Symbol.iterator]()); // Returns true
1725 ### `util.types.isModuleNamespaceObject(value)`
1739 util.types.isModuleNamespaceObject(ns); // Returns true
1742 ### `util.types.isNativeError(value)`
1753 util.types.isNativeError(new Error()); // Returns true
1754 util.types.isNativeError(new TypeError()); // Returns true
1755 util.types.isNativeError(new RangeError()); // Returns true
1758 ### `util.types.isNumberObject(value)`
1770 util.types.isNumberObject(0); // Returns false
1771 util.types.isNumberObject(new Number(0)); // Returns true
1774 ### `util.types.isPromise(value)`
1785 util.types.isPromise(Promise.resolve(42)); // Returns true
1788 ### `util.types.isProxy(value)`
1801 util.types.isProxy(target); // Returns false
1802 util.types.isProxy(proxy); // Returns true
1805 ### `util.types.isRegExp(value)`
1816 util.types.isRegExp(/abc/); // Returns true
1817 util.types.isRegExp(new RegExp('abc')); // Returns true
1820 ### `util.types.isSet(value)`
1831 util.types.isSet(new Set()); // Returns true
1834 ### `util.types.isSetIterator(value)`
1847 util.types.isSetIterator(set.keys()); // Returns true
1848 util.types.isSetIterator(set.values()); // Returns true
1849 util.types.isSetIterator(set.entries()); // Returns true
1850 util.types.isSetIterator(set[Symbol.iterator]()); // Returns true
1853 ### `util.types.isSharedArrayBuffer(value)`
1863 desirable to test for both; See [`util.types.isAnyArrayBuffer()`][] for that.
1866 util.types.isSharedArrayBuffer(new ArrayBuffer()); // Returns false
1867 util.types.isSharedArrayBuffer(new SharedArrayBuffer()); // Returns true
1870 ### `util.types.isStringObject(value)`
1882 util.types.isStringObject('foo'); // Returns false
1883 util.types.isStringObject(new String('foo')); // Returns true
1886 ### `util.types.isSymbolObject(value)`
1899 util.types.isSymbolObject(symbol); // Returns false
1900 util.types.isSymbolObject(Object(symbol)); // Returns true
1903 ### `util.types.isTypedArray(value)`
1914 util.types.isTypedArray(new ArrayBuffer()); // Returns false
1915 util.types.isTypedArray(new Uint8Array()); // Returns true
1916 util.types.isTypedArray(new Float64Array()); // Returns true
1921 ### `util.types.isUint8Array(value)`
1932 util.types.isUint8Array(new ArrayBuffer()); // Returns false
1933 util.types.isUint8Array(new Uint8Array()); // Returns true
1934 util.types.isUint8Array(new Float64Array()); // Returns false
1937 ### `util.types.isUint8ClampedArray(value)`
1948 util.types.isUint8ClampedArray(new ArrayBuffer()); // Returns false
1949 util.types.isUint8ClampedArray(new Uint8ClampedArray()); // Returns true
1950 util.types.isUint8ClampedArray(new Float64Array()); // Returns false
1953 ### `util.types.isUint16Array(value)`
1964 util.types.isUint16Array(new ArrayBuffer()); // Returns false
1965 util.types.isUint16Array(new Uint16Array()); // Returns true
1966 util.types.isUint16Array(new Float64Array()); // Returns false
1969 ### `util.types.isUint32Array(value)`
1980 util.types.isUint32Array(new ArrayBuffer()); // Returns false
1981 util.types.isUint32Array(new Uint32Array()); // Returns true
1982 util.types.isUint32Array(new Float64Array()); // Returns false
1985 ### `util.types.isWeakMap(value)`
1996 util.types.isWeakMap(new WeakMap()); // Returns true
1999 ### `util.types.isWeakSet(value)`
2010 util.types.isWeakSet(new WeakSet()); // Returns true
2013 ### `util.types.isWebAssemblyCompiledModule(value)`
2028 util.types.isWebAssemblyCompiledModule(module); // Returns true
2036 ### `util._extend(target, source)`
2047 The `util._extend()` method was never intended to be used outside of internal
2053 ### `util.isArray(object)`
2069 const util = require('util');
2071 util.isArray([]);
2073 util.isArray(new Array());
2075 util.isArray({});
2079 ### `util.isBoolean(object)`
2093 const util = require('util');
2095 util.isBoolean(1);
2097 util.isBoolean(0);
2099 util.isBoolean(false);
2103 ### `util.isBuffer(object)`
2117 const util = require('util');
2119 util.isBuffer({ length: 0 });
2121 util.isBuffer([]);
2123 util.isBuffer(Buffer.from('hello world'));
2127 ### `util.isDate(object)`
2133 > Stability: 0 - Deprecated: Use [`util.types.isDate()`][] instead.
2141 const util = require('util');
2143 util.isDate(new Date());
2145 util.isDate(Date());
2147 util.isDate({});
2151 ### `util.isError(object)`
2157 > Stability: 0 - Deprecated: Use [`util.types.isNativeError()`][] instead.
2166 const util = require('util');
2168 util.isError(new Error());
2170 util.isError(new TypeError());
2172 util.isError({ name: 'Error', message: 'an error occurred' });
2181 const util = require('util');
2184 util.isError(obj);
2187 util.isError(obj);
2191 ### `util.isFunction(object)`
2206 const util = require('util');
2211 util.isFunction({});
2213 util.isFunction(Foo);
2215 util.isFunction(Bar);
2219 ### `util.isNull(object)`
2234 const util = require('util');
2236 util.isNull(0);
2238 util.isNull(undefined);
2240 util.isNull(null);
2244 ### `util.isNullOrUndefined(object)`
2260 const util = require('util');
2262 util.isNullOrUndefined(0);
2264 util.isNullOrUndefined(undefined);
2266 util.isNullOrUndefined(null);
2270 ### `util.isNumber(object)`
2284 const util = require('util');
2286 util.isNumber(false);
2288 util.isNumber(Infinity);
2290 util.isNumber(0);
2292 util.isNumber(NaN);
2296 ### `util.isObject(object)`
2313 const util = require('util');
2315 util.isObject(5);
2317 util.isObject(null);
2319 util.isObject({});
2321 util.isObject(() => {});
2325 ### `util.isPrimitive(object)`
2342 const util = require('util');
2344 util.isPrimitive(5);
2346 util.isPrimitive('foo');
2348 util.isPrimitive(false);
2350 util.isPrimitive(null);
2352 util.isPrimitive(undefined);
2354 util.isPrimitive({});
2356 util.isPrimitive(() => {});
2358 util.isPrimitive(/^$/);
2360 util.isPrimitive(new Date());
2364 ### `util.isRegExp(object)`
2378 const util = require('util');
2380 util.isRegExp(/some regexp/);
2382 util.isRegExp(new RegExp('another regexp'));
2384 util.isRegExp({});
2388 ### `util.isString(object)`
2402 const util = require('util');
2404 util.isString('');
2406 util.isString('foo');
2408 util.isString(String('foo'));
2410 util.isString(5);
2414 ### `util.isSymbol(object)`
2428 const util = require('util');
2430 util.isSymbol(5);
2432 util.isSymbol('foo');
2434 util.isSymbol(Symbol('foo'));
2438 ### `util.isUndefined(object)`
2452 const util = require('util');
2455 util.isUndefined(5);
2457 util.isUndefined(foo);
2459 util.isUndefined(null);
2463 ### `util.log(string)`
2473 The `util.log()` method prints the given `string` to `stdout` with an included
2477 const util = require('util');
2479 util.log('Timestamped message.');
2485 [Customizing `util.inspect` colors]: #util_customizing_util_inspect_colors
2523 [`util.format()`]: #util_util_format_format_args
2524 [`util.inspect()`]: #util_util_inspect_object_options
2525 [`util.promisify()`]: #util_util_promisify_original
2526 [`util.types.isAnyArrayBuffer()`]: #util_util_types_isanyarraybuffer_value
2527 [`util.types.isArrayBuffer()`]: #util_util_types_isarraybuffer_value
2528 [`util.types.isDate()`]: #util_util_types_isdate_value
2529 [`util.types.isNativeError()`]: #util_util_types_isnativeerror_value
2530 [`util.types.isSharedArrayBuffer()`]: #util_util_types_issharedarraybuffer_value
2538 [util.inspect.custom]: #util_util_inspect_custom