Write formatted JSON in Node.js

Question

I'm using Node.js to POST JSON to PostBin but the data is being wrongly formated (as you can see here: http://www.postbin.org/1cpndqw).

This is the code I'm using for tesT:

var http = require('http'); var options = { host: 'www.postbin.org', port: 80, path: '/1cpndqw', method: 'POST' }; var req = http.request(options, function(res) { console.log('STATUS: ' + res.statusCode); console.log('HEADERS: ' + JSON.stringify(res.headers)); res.setEncoding('utf8'); res.on('data', function (chunk) { console.log('BODY: ' + chunk); }); }); req.write(JSON.stringify({ a:1, b:2, c:3 }, null, 4)); req.end();

{"a":1,"b":2,"c":3} did you fix your issue? It seems like you got the data posted correctly. — Raynos
– Raynos, Commented Apr 17, 2011 at 14:16
The data is correct but "ugly", I want to send like this, easier to understand: postbin.org/1ijyltn#xa6rim — donald
– donald, Commented Apr 17, 2011 at 14:18

T.J. Crowder · Accepted Answer · 2014-10-17 11:46:15Z

354

Use JSON.stringify(object, null, 4) where 4 is the number of spaces to use as the unit of indentation. You can also use "\t" if you want tabs. This is actually part of the ECMAScript 5 specification, and is documented on MDN.

edited Oct 17, 2014 at 11:46

T.J. Crowder

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answered Jun 30, 2012 at 17:25

Peter Lyons

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4 Comments

mrjf Over a year ago

Wow, thanks! I wonder why this isn't documented anymore. I assumed it wasn't available.

Peter Lyons Over a year ago

Yeah, it's odd. Maybe it's on the road to deprecation or something? Just a documentation oversight? Not sure.

Matthew Flaschen Over a year ago

@PeterLyons, this is in the ECMAScript 5 spec. Maybe they just didn't feel like documenting things that weren't node-specific.

Dave Newton Over a year ago

FWIW, this appears to be documented essentially everywhere, and does not appear to be Node-specific, as of now.

Community · Accepted Answer · 2017-05-23 12:25:45Z

Well, primarily because JSON doesn't care how it's formatted, and you aren't doing any formatting yourself. What you need is a javascript prettyprinter, if you care, but the first question is "Why do you care?"

Here's a prettyprinting code from the Javascript Recipes.

Actually there's a whole bunch of different examples here on SO.

UPDATE

Okay, so now it's doing what you want, let's ask if you're doing the right thing. As several people have pointed out, you needn't transmit those extra newlines and tabs, or spaces; the efficiency cost is small, probably in the neighborhood of 2-5 percent, but you never know when you might need a couple percent.

On the other hand, I agree completely that it's a lot more convenient to be able to read the JSON output as prettyprinted text. But there's another solution -- you're still probably using a browser to look at these results, so instead of prettyprinting it for transmission, use a client-side prettyprinter. I use JSONView for Chrome and JSONView in Firefox. Many debuggers will also prettyprint the JSON results for you as well.

For transmission purposes, you don't want to be sending/receiving the extra formatting data. The JSON with extra whitespace means nothing different to the machine... it only matters to a human that needs to understand it. Ideally, you only want to pretty print it when you actually have a person that needs to look at it.
@donald why do you care about how it looks? JSON is raw data. You do not care about whitespace.
IT worked as: console.log(JSON.stringify({ a:1, b:2, c:3 }, null, '\t')); in the console, but still, PostBin does not make it right. Maybe it's their problem?
developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

Fritz Dodoo · Accepted Answer · 2017-03-29 20:18:27Z

I used a two step process that I found to work:

var output = JSON.parse(insert_json_here); var print_to_file = JSON.stringify(output, null, "\t")

Dave Dopson · Accepted Answer · 2012-04-29 21:20:57Z

You should check out underscore-cli - it's a command-line tool for inspecting and processing JSON data.

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