A compilation of the many useful answers from (at least) Node.js v0.10.33
(stable) / v0.11.14
(unstable) presumably through (at least) v7.7.4
(the version current as of the latest update to this answer).
tl;dr
util.inspect()
is at the heart of diagnostic output: console.log()
and console.dir()
as well as the Node.js REPL use util.inspect()
implicitly, so it's generally not necessary to require('util')
and call util.inspect()
directly.
To get the desired output for the example in the question:
console.dir(myObject, { depth: null }); // `depth: null` ensures unlimited recursion
Details below.
- The REPL: implicitly prints any expression's return value with
util.inspect()
with syntax coloring;
i.e., just typing a variable's name and hitting Enter will print an inspected version of its value; e.g.:
o = { one: 1, two: 'deux', foo: function(){} } // echoes the object definition with syntax coloring.
util.inspect()
automatically (and invariably) pretty-prints object and array representations, but produces multiline output only when needed - if everything fits on one line, only 1 line is printed.
By default, output is wrapped at around 60 characters thanks, Shrey
, regardless of whether the output is sent to a file or a terminal. In practice, since line breaks only happen at property boundaries, you will often end up with shorter lines, but they can also be longer (e.g., with long property values).
In v6.3.0+ you can use the breakLength
option to override the 60-character limit; if you set it to Infinity
, everything is output on a single line.
If you want more control over pretty-printing, consider using JSON.stringify()
with a 3rd argument, but note the following:
- Fails with objects that have circular references, such as
module
in the global context.
- Methods (functions) will by design NOT be included.
- You can't opt into showing hidden (non-enumerable) properties.
- Example call:
JSON.stringify({ one: 1, two: 'deux', three: true}, undefined, 2); // creates a pretty-printed multiline JSON representation indented with 2 spaces
util.inspect()
options object (2nd argument):
source: http://nodejs.org/api/util.html#util_util_format_format
An optional options object may be passed that alters certain aspects of the formatted string:
showHidden
- if
true
, then the object's non-enumerable properties [those designated not to show up when you use for keys in obj
or Object.keys(obj)
] will be shown too. Defaults to false
.
depth
- tells inspect how many times to recurse while formatting the object. This is useful for inspecting large complicated objects. Defaults to 2. To make it recurse indefinitely, pass
null
.
colors
- if true, then the output will be styled with ANSI color codes. Defaults to
false
. Colors are customizable [... - see link].
customInspect
- if
false
, then custom inspect()
functions defined on the objects being inspected won't be called. Defaults to true
.
util.format()
format-string placeholders (1st argument)
source: http://nodejs.org/api/util.html#util_util_format_format
%s
- String.
%d
- Number (both integer and float).
%j
- JSON.
%
- single percent sign ('%'). This does not consume an argument.
0
Created by mklement0 on 2020-03-10 18:52:29 +0000 UTC
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