How can I get the full object in Node.js's console.log(), rather than '[Object]'?
Javascriptnode.jsDebuggingconsole.logJavascript Problem Overview
I have this object:
const myObject = {
"a":"a",
"b":{
"c":"c",
"d":{
"e":"e",
"f":{
"g":"g",
"h":{
"i":"i"
}
}
}
}
};
But when I try to show it using console.log(myObject)
, I receive this output:
{ a: 'a', b: { c: 'c', d: { e: 'e', f: [Object] } } }
How can I get the full object, including the content of property f
?
Javascript Solutions
Solution 1 - Javascript
You need to use util.inspect()
:
const util = require('util')
console.log(util.inspect(myObject, {showHidden: false, depth: null, colors: true}))
// alternative shortcut
console.log(util.inspect(myObject, false, null, true /* enable colors */))
Outputs
{ a: 'a', b: { c: 'c', d: { e: 'e', f: { g: 'g', h: { i: 'i' } } } } }
See util.inspect()
docs.
Solution 2 - Javascript
You can use JSON.stringify
, and get some nice indentation as well as perhaps easier to remember syntax.
console.log(JSON.stringify(myObject, null, 4));
{
"a": "a",
"b": {
"c": "c",
"d": {
"e": "e",
"f": {
"g": "g",
"h": {
"i": "i"
}
}
}
}
}
The third argument sets the indentation level, so you can adjust that as desired.
More detail here in JSON stringify MDN docs if needed.
Solution 3 - Javascript
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). Tip of the hat to Rory O'Kane for his help.
tl;dr
To get the desired output for the example in the question, use console.dir()
:
console.dir(myObject, { depth: null }); // `depth: null` ensures unlimited recursion
Why not util.inspect()
? Because it’s already at the heart of diagnostic output: console.log()
and console.dir()
as well as the Node.js REPL use util.inspect()
implicitly. It’s generally not necessary to require('util')
and call util.inspect()
directly.
Details below.
-
console.log()
(and its alias,console.info()
):- If the 1st argument is NOT a format string:
util.inspect()
is automatically applied to every argument:o = { one: 1, two: 'deux', foo: function(){} }; console.log(o, [1,2,3]) // -> '{ one: 1, two: 'deux', foo: [Function] } [ 1, 2, 3 ]'
- Note that you cannot pass options through
util.inspect()
in this case, which implies 2 notable limitations:- Structural depth of the output is limited to 2 levels (the default).
- Since you cannot change this with
console.log()
, you must instead useconsole.dir()
:console.dir(myObject, { depth: null }
prints with unlimited depth; see below.
- Since you cannot change this with
- You can’t turn syntax coloring on.
- Structural depth of the output is limited to 2 levels (the default).
- If the 1st argument IS a format string (see below): uses
util.format()
to print the remaining arguments based on the format string (see below); e.g.:o = { one: 1, two: 'deux', foo: function(){} }; console.log('o as JSON: %j', o) // -> 'o as JSON: {"one":1,"two":"deux"}'
- Note:
- There is NO placeholder for representing objects
util.inspect()
-style. - JSON generated with
%j
is NOT pretty-printed.
- There is NO placeholder for representing objects
- If the 1st argument is NOT a format string:
-
- Accepts only 1 argument to inspect, and always applies
util.inspect()
– essentially, a wrapper forutil.inspect()
without options by default; e.g.:o = { one: 1, two: 'deux', foo: function(){} }; console.dir(o); // Effectively the same as console.log(o) in this case.
- Node.js v0.11.14+: The optional 2nd argument specifies options for
util.inspect()
– see below; e.g.:console.dir({ one: 1, two: 'deux'}, { colors: true }); // Node 0.11+: Prints object representation with syntax coloring.
- Accepts only 1 argument to inspect, and always applies
- 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(){} } // The REPL echoes the object definition with syntax coloring.
util.inspect()
automatically pretty-prints object and array representations, but produces multiline output only when needed.
-
The pretty-printing behavior can be controlled by the
compact
property in the optionaloptions
argument;false
uses multi-line output unconditionally, whereastrue
disables pretty-printing altogether; it can also be set to a number (the default is3
) to control the conditional multi-line behavior – see the docs. -
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 toInfinity
, 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):
An optional options object may be passed that alters certain aspects of the formatted string; some of the properties supported are:
See the latest Node.js docs for the current, full list.
-
showHidden
- if
true
, then the object's non-enumerable properties [those designated not to show up when you usefor keys in obj
orObject.keys(obj)
] will be shown too. Defaults tofalse
.
- if
-
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
.
- 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
-
colors
- if true, then the output will be styled with ANSI color codes. Defaults to
false
. Colors are customizable [… – see link].
- if true, then the output will be styled with ANSI color codes. Defaults to
-
customInspect
- if
false
, then custominspect()
functions defined on the objects being inspected won't be called. Defaults totrue
.
- if
util.format()
format-string placeholders (1st argument)
Some of the supported placeholders are:
See the latest Node.js docs for the current, full list.
%s
– String.%d
– Number (both integer and float).%j
– JSON.%%
– single percent sign (‘%’). This does not consume an argument.
Solution 4 - Javascript
Another simple method is to convert it to json
console.log('connection : %j', myObject);
Solution 5 - Javascript
Try this:
console.dir(myObject,{depth:null})
Solution 6 - Javascript
Since Node.js 6.4.0, this can be elegantly solved with util.inspect.defaultOptions
:
require("util").inspect.defaultOptions.depth = null;
console.log(myObject);
Solution 7 - Javascript
perhaps console.dir
is all you need.
http://nodejs.org/api/console.html#console_console_dir_obj
> Uses util.inspect on obj and prints resulting string to stdout.
use util option if you need more control.
Solution 8 - Javascript
Both of these usages can be applied:
// more compact, and colour can be applied (better for process managers logging)
console.dir(queryArgs, { depth: null, colors: true });
// get a clear list of actual values
console.log(JSON.stringify(queryArgs, undefined, 2));
Solution 9 - Javascript
A good way to inspect objects is to use node --inspect option with Chrome DevTools for Node.
node.exe --inspect www.js
Open chrome://inspect/#devices
in chrome and click Open dedicated DevTools for Node
Now every logged object is available in inspector like regular JS running in chrome.
There is no need to reopen inspector, it connects to node automatically as soon as node starts or restarts. Both --inspect and Chrome DevTools for Node may not be available in older versions of Node and Chrome.
Solution 10 - Javascript
You can also do
console.log(JSON.stringify(myObject, null, 3));
Solution 11 - Javascript
I think this could be useful for you.
const myObject = {
"a":"a",
"b":{
"c":"c",
"d":{
"e":"e",
"f":{
"g":"g",
"h":{
"i":"i"
}
}
}
}
};
console.log(JSON.stringify(myObject, null, '\t'));
As mentioned in this answer:
> JSON.stringify
's third parameter defines white-space insertion for
> pretty-printing. It can be a string or a number (number of spaces).
Solution 12 - Javascript
You can simply add an inspect()
method to your object which will override the representation of object in console.log
messages
eg:
var myObject = {
"a":"a",
"b":{
"c":"c",
"d":{
"e":"e",
"f":{
"g":"g",
"h":{
"i":"i"
}
}
}
}
};
myObject.inspect = function(){ return JSON.stringify( this, null, ' ' ); }
then, your object will be represented as required in both console.log and node shell
Update:
object.inspect has been deprecated ( https://github.com/nodejs/node/issues/15549). Use myObject[util.inspect.custom] instead:
const util = require('util')
var myObject = {
/* nested properties not shown */
}
myObject[util.inspect.custom] = function(){ return JSON.stringify( this, null, 4 ); }
console.log(util.inspect(myObject))
Solution 13 - Javascript
JSON.stringify()
let myVar = {a: {b: {c: 1}}};
console.log(JSON.stringify( myVar, null, 4 ))
Great for deep inspection of data objects. This approach works on nested arrays and nested objects with arrays.
Solution 14 - Javascript
A simple trick would be use debug
module to add DEBUG_DEPTH=null
as environment variable when running the script
Ex.
DEBUG=* DEBUG_DEPTH=null node index.js
In you code
const debug = require('debug');
debug("%O", myObject);
Solution 15 - Javascript
The node REPL has a built-in solution for overriding how objects are displayed, see here.
> The REPL module internally uses util.inspect()
, when printing values.
> However, util.inspect
delegates the call to the object's inspect()
> function, if it has one.
Solution 16 - Javascript
Easiest option:
console.log('%O', myObject);
Solution 17 - Javascript
If you're looking for a way to show the hidden items in you array, you got to pass maxArrayLength: Infinity
console.log(util.inspect(value, { maxArrayLength: Infinity }));
Solution 18 - Javascript
Use a logger
> Don't try to reinvent the wheel
util.inspect()
, JSON.stringify()
and console.dir()
are useful tools for logging an object while playing in the browser console.
If you are serious about Node.js development, you should definitely use a logger. Using it you can add all the logs you want for debugging and monitoring your application. Then just change the logging level of your logger to keep only the production logs visible.
Additionaly they have already solved all the annoying issues related to logging, like: circular objects, formatting, log levels, multiple outputs and performance.
Use a modern logger
pino
is a fast and modern logger for Node.js that has sane defaults to handle circular object/references like depthLimit
and edgeLimit
. It supports child loggers, transports and a pretty printed output.
Moreover, it has 8 default logging levels that you can customize using the customLevels
option:
fatal
error
warn
info
debug
trace
silent
Install it
npm install pino
Use it
const logger = require('pino')()
logger.info('hello world')
Configure it
const logger = pino({
depthLimit: 10,
edgeLimit: 200,
customLevels: {
foo: 35
}
});
logger.foo('hi')