ChatGPT解决这个技术问题 Extra ChatGPT

How can I get the full object in Node.js's console.log(), rather than '[Object]'?

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?

Note that back in 2012 this was a problem in need of a solution, but this has (long) since been solved with the introduction of console.dir, which takes an options object that lets you specify the printing depth, with null for unlimited depth: console.dir(yourObject, { depth: null });. The highest voted answers for this question were all great answers back when they were written, but have since become obsolete over the course of a decade of improvements. The modern answer is simply "use console.dir".

m
mikemaccana

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' } } } } }

Nice solution. Though no need to specify {showHidden: false} as long as it defaults to false.
Good to know; not sure when it was introduced, but as of at least node v0.10.33 console.log() implicitly applies util.inspect() to its arguments, assuming the 1st one is not a format string. If you're happy with util.inspect()'s default options, simply console.log(myObject) will do - no need to require util; console.dir() does the same, but accepts only ` object to inspect; as of at least v0.11.14, you can pass the options object for util.inspect() as the 2nd argument; my answer has more details.
@mklement0 I have node v5.3.0 and when I console.log(obj) it still prints [Object] for deeply nested objects :( I really wish it would behave as you describe.
@SSH: console.log() is invariably limited to 2 levels (because it uses util.inspect()'s default without allowing you to change it); console.dir() has the same limit by default, but you can pass in an options object as the 2nd argument to change that (which is passed through to util.inspect(); note that console.dir() can only ever print 1 object at a time, however. To print with unlimited depth, use console.dir(myObject, { depth: null }).
console.dir(myObject, { depth: null }) is work for me
3
3 revs, 3 users 87% user1106925

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.


also +1 for line breaks and indentation - almost always desired for me personally
Note that you cannot JSON.stringify objects with circular references. Like it would occur with DOM objects, for example. Stringify will throw an "Error: Converting circular structure to JSON".
this isn't the full object. objects containing only functions will be {}. Of course that may be a positive or a negative depending on what you want to print out.
console.log(JSON.stringify(myObject, null, 4)); pretty cool! https://gist.github.com/xgqfrms-GitHub/92aa2b00249f15084d24aa2e0a5d0300
In my case i get this error TypeError: Converting circular structure to JSON
R
Rory O'Kane

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 use console.dir(): console.dir(myObject, { depth: null } prints with unlimited depth; see below. You can’t turn syntax coloring on. 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.

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 use console.dir(): console.dir(myObject, { depth: null } prints with unlimited depth; see below. You can’t turn syntax coloring on.

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 use console.dir(): console.dir(myObject, { depth: null } prints with unlimited depth; see below. You can’t turn syntax coloring on.

Structural depth of the output is limited to 2 levels (the default). Since you cannot change this with console.log(), you must instead use console.dir(): console.dir(myObject, { depth: null } prints with unlimited depth; see below.

Since you cannot change this with console.log(), you must instead use console.dir(): console.dir(myObject, { depth: null } prints with unlimited depth; see below.

You can’t turn syntax coloring on.

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.

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 util.inspect()-style.

JSON generated with %j is NOT pretty-printed.

console.dir(): Accepts only 1 argument to inspect, and always applies util.inspect() – essentially, a wrapper for util.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 util.inspect() – essentially, a wrapper for util.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.

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.

console.dir({ one: 1, two: 'deux'}, { colors: true }); // Node 0.11+: Prints object representation with syntax coloring.

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.

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 optional options argument; false uses multi-line output unconditionally, whereas true disables pretty-printing altogether; it can also be set to a number (the default is 3) 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 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

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 use for keys in obj or Object.keys(obj)] will be shown too. Defaults to false.

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.

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].

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.

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)

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.


One way to simplify this would be to do a small named function to do console.dir(...) without all the typing: show = (v, depth=null)=> console.dir(v,{depth:depth}) and then call it like so show(variable) or show(variable, depth=1).
Thanks for this complete answer => THE BEST SOLUTION YOU GAVE : JSON.stringify({ one: 1, two: 'deux', three: true}, undefined, 2);
n
niksmac

Another simple method is to convert it to json

console.log('connection : %j', myObject);

Nice trick but the output won't be prettified, which makes it hard to read for large objects (the point of the question).
still very useful, and quicker to copy and paste into jsonlint.com than requiring utils :)
I think this one is great when you have an editor that will format json for you but you just need to copy it out from REPL
This is very handy and helpful if the object is small
s
silverwind

Since Node.js 6.4.0, this can be elegantly solved with util.inspect.defaultOptions:

require("util").inspect.defaultOptions.depth = null;
console.log(myObject);

M
MarmiK

Try this:

console.dir(myObject,{depth:null})

L
Luke W

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.


As of (at least) v0.11.14, you can pass an options object as the 2nd argument, which is passed to util.inspect().
R
Rory O'Kane

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));

A
Ali

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.

https://i.stack.imgur.com/cBoMu.jpg

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.


A message for me: try that out -> node.exe --inspect index.js
This should be on top. best answer. :)
e
evandrix

You can also do

console.log(JSON.stringify(myObject, null, 3));

u
user1063287

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).


a
apollo

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))

S
Stephen Blum

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.


l
lifeisfoo

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')

C
Chintan

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);

@Bala You will need to install "debug" module in your project "npm install debug --save"
L
Lloyd

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.


L
LF00

Easiest option:

console.log('%O', myObject);


This doesn't solve the problem of printing myObject to an arbitrary depth
L
Lukas

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 }));

Also works with console.dir.