util

Members

isArray static

isError static

isBuffer static

Methods

format(f) → string static

Returns a formatted string using the first argument as a printf-like format.

The first argument is a string that contains zero or more placeholders. Each placeholder is replaced with the converted value from its corresponding argument. Supported placeholders are:

  • %s - String.
  • %d - Number (both integer and float).
  • %j - JSON.
  • % - single percent sign ('%'). This does not consume an argument.

If the placeholder does not have a corresponding argument, the placeholder is not replaced:

 util.format('%s:%s', 'foo'); // 'foo:%s'

If there are more arguments than placeholders, the extra arguments are converted to strings with util.inspect() and these strings are concatenated, delimited by a space:

 util.format('%s:%s', 'foo', 'bar', 'baz'); // 'foo:bar baz'

If the first argument is not a format string then util.format() returns a string that is the concatenation of all its arguments separated by spaces. Each argument is converted to a string with util.inspect():

 util.format(1, 2, 3); // '1 2 3'
Arguments:
  1. f

inspect(obj, opts) inner

Echos the value of a value. Tries to print the value out in the best way possible given the different types.
Arguments:
  1. obj (Object)  The object to print out.
  2. opts (Object)  Optional options object that alters the output.

isBoolean(arg) → boolean inner

Arguments:
  1. arg

isNull(arg) → boolean inner

Arguments:
  1. arg

isNullOrUndefined(arg) → boolean inner

Arguments:
  1. arg

isNumber(arg) → boolean inner

Arguments:
  1. arg

isString(arg) → boolean inner

Arguments:
  1. arg

isSymbol(arg) → boolean inner

Arguments:
  1. arg

isUndefined(arg) → boolean inner

Arguments:
  1. arg

isRegExp(re) → boolean inner

Arguments:
  1. re

isObject(arg) → boolean inner

Arguments:
  1. arg

isDate(d) → boolean inner

Arguments:
  1. d

isFunction(arg) → boolean inner

Arguments:
  1. arg

isPrimitive(arg) → boolean inner

Arguments:
  1. arg

log(msg) static

Output with timestamp on stdout.
Arguments:
  1. msg (String)

inherits(ctor, superCtor) static

Inherit the prototype methods from one constructor into another.

The Function.prototype.inherits from lang.js rewritten as a standalone function (not on Function.prototype). NOTE: If this file is to be loaded during bootstrapping this function needs to be rewritten using some native functions as prototype setup using normal JavaScript does not work as expected during bootstrapping (see mirror.js in r114903).

Arguments:
  1. ctor (function)  Constructor function which needs to inherit the prototype.
  2. superCtor (function)  Constructor function to inherit prototype from.
Throws:

Will error if either constructor is null, or if the super constructor lacks a prototype.

Type
TypeError

print(…arguments) inner

A synchronous output function. Will block the process, cast each argument to a string then output to stdout. Does not place newlines after each argument:

 util.print('one', 'two', 3); // onetwo3
Arguments:
  1. ...arguments (*)
Deprecated:
  • Use console.log instead

puts(…arguments) inner

A synchronous output function. Will block the process and output all arguments to stdout with newlines after each argument.

 util.puts('one', 'two', 3); // one
                             // two
                             // 3
Arguments:
  1. ...arguments (*)
Deprecated:
  • Use console.log instead

debug(msg) inner

Will block the process and output string immediately to stderr:

 require('util').debug('message on stderr');
Arguments:
  1. msg (*)
Deprecated:
  • Use console.error instead

error(…arguments) inner

Same as util#debug except this will output all arguments immediately to stderr.
Arguments:
  1. ...arguments (*)
Deprecated:
  • Use console.error instead