How do you log content of a JSON object in Node.js?

Question

Is it possible to print an objects contents e.g. methods and attributes in Node.js?

At the moment I'm trying to print the session object and get the following:

console.log("Session:" + session);
> Session:[object Object]

Maybe in a similar way to print_r(array) in PHP, or using .toString in Java.

For a more intuitive and visual output of objects take a look at nodedump: https://github.com/ragamufin/nodedump — ragamufin, Oct 03 '13 at 23:41

score 304 · Accepted Answer · edited Jul 16 '17 at 10:26

304

Try this one:

console.log("Session: %j", session);

If the object could be converted into JSON, that will work.

edited Jul 16 '17 at 10:26

Peter Mortensen

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answered Sep 15 '11 at 08:59

Alexander Sulfrian

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I am trying to do this for the request object but it shows error TypeError: Converting circular structure to JSON Is there any way to limit the depth – Neil May 17 '13 at 10:29
anyway to pretty print this? – chovy Aug 13 '13 at 06:24
6

@chovy: something like this might work: console.log(JSON.stringify(json, null, 4)); – Eric Brandel Sep 03 '13 at 21:05
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this worked for me: `console.log("Session: %O", session);` https://developer.mozilla.org/en-US/docs/Web/API/console#Outputting_text_to_the_console – JP Lew Jun 12 '19 at 22:02
this this console.log no fuss drop-in replacement https://www.npmjs.com/package/console-log-json – 7wp May 29 '23 at 20:07

score 154 · Answer 2 · edited Sep 17 '14 at 07:58

154

function prettyJSON(obj) {
    console.log(JSON.stringify(obj, null, 2));
}

// obj -> value to convert to a JSON string
// null -> (do nothing)
// 2 -> 2 spaces per indent level

JSON.stringify on MDN

edited Sep 17 '14 at 07:58

Jake Berger

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answered Jun 27 '12 at 19:46

ccgillett

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score 33 · Answer 3 · answered Apr 13 '12 at 09:51

33

To have an output more similar to the raw console.log(obj) I usually do use console.log('Status: ' + util.inspect(obj)) (JSON is slightly different).

answered Apr 13 '12 at 09:51

lapo

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This gives "util is not defined". You must `var util = require("util") first. Also, the sub-objects still turn out as [Object] and not the JSON string that represents them. – juanpaco May 01 '13 at 12:26
14

To remove the depth limit, use: `require('util').inspect(obj, {depth:null})` – lapo May 02 '13 at 10:57

Marwen Trabelsi · Answer 4 · 2015-06-23T05:50:06.233

30

This will work with any object:

    var util = require("util");
    console.log(util.inspect(myObject, {showHidden: false, depth: null}));

edited Jun 23 '15 at 05:50

answered Aug 04 '14 at 05:45

Marwen Trabelsi

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This works great for error objects. None of their properties show up in the other solutions. – Chris Jun 22 '15 at 21:14
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This just hangs for me. I think circular references in an object crashes it – Richard May 19 '16 at 15:25
@Richard it probably hang(ed) for you due to the depth option being set to `null`. Inspect has built-in treatment for circular references. – cvsguimaraes Aug 15 '17 at 21:16

score 7 · Answer 5 · answered Dec 17 '13 at 02:56

7

console.dir() is the most direct way.

answered Dec 17 '13 at 02:56

rainabba

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console.dir(someJsonObject); still leaves nested objects unprinted, for me. – nyarasha Nov 10 '15 at 17:28
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I think it won't drill into objects through their prototype and it won't deal with certain recursion. You're either going to have to do something like console.log(JSON.stringify()) or something more specific to your object if .dir() isn't sufficient. If you have more info about the object, perhaps more specific advice can be given. – rainabba Nov 11 '15 at 20:43
It can take the same options as util.inspect. Add {depth:null} – nikc.org Feb 26 '17 at 09:50
I like the formatting (a nice compromise between readability and compactness) but be warned that this does not output valid JSON: * single quotes around strings * object keys are not quoted if they're words – bart Mar 11 '23 at 12:10

score 2 · Answer 6 · answered May 25 '22 at 16:12

2

console.dir with the depth argument set will do the trick. This will print JSON objects to any arbitrary depth. Depth:null means print every level.

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

answered May 25 '22 at 16:12

john k

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score 0 · Answer 7 · answered May 16 '18 at 13:14

0

console.log(obj);

Run: node app.js > output.txt

answered May 16 '18 at 13:14

Rostyslav Bornitskyi

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score 0 · Answer 8 · answered Nov 06 '18 at 11:08

0

This will for most of the objects for outputting in nodejs console

var util = require('util')
function print (data){
  console.log(util.inspect(data,true,12,true))
  
}

print({name : "Your name" ,age : "Your age"})

answered Nov 06 '18 at 11:08

manoj kumar

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score 0 · Answer 9 · answered May 29 '23 at 20:06

If you are still looking for some options, there is a NPM package that might help you, a drop-in replacement for console.log called console-log-json. The nice thing about it is that it will create consistent JSON formatted logs, despite the fact that you can throw at console.log() any number of parameters in any order, including other JSON objects as well as Error objects and plain strings.

It also handles automatically adding some extra helpful attributes such as time stamps and file where the console.log() was called from, etc..

These all get printed to STDOUT so any log shipping and aggregator can pick it up and parse the JSON.

How do you log content of a JSON object in Node.js?

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