CODEWITHSUNDEEP
javascriptnode.jsjsonnpmreadfile
Hemã Vidal
Hemã Vidal

Reputation: 1882

Read json file ignoring custom comments

How can i read this file 'file.json':

# Comment01
# Comment02
{
   "name": "MyName"
}

and retrieve the json without comments?

I'm using this code:

var fs = require('fs');
var obj;
fs.readFile('./file.json', 'utf8', function (err, data) { 
  if (err) throw err;
  obj = JSON.parse(data);
});

it returns this error:

SyntaxError: Unexpected token # in JSON at position 0

Have npm some package to solve this question?

Upvotes: 9

Views: 8721

Answers (6)

PDHide
PDHide

Reputation: 19949

let json = require('json5')
let fs = require('fs-extra')

let a = json.parse(fs.readFileSync("./tsconfig.json"))
console.log(a)

you can use json5 module

Upvotes: 2

Robby Polana
Robby Polana

Reputation: 9

Javascript has a comment remover built-in, no need for an extra package. I wouldn't do this for user input though.

eval(
  'var myjsonfile=' +
    require('fs')
      .readFileSync('./myjsonfile.json')
      .toString(),
);
console.log(myjsonfile);

Upvotes: -3

Hemã Vidal
Hemã Vidal

Reputation: 1882

The perfect package for this problem is https://www.npmjs.com/package/hjson

hjsonText input:


{
  # hash style comments
  # (because it's just one character)

  // line style comments
  // (because it's like C/JavaScript/...)

  /* block style comments because
     it allows you to comment out a block */

  # Everything you do in comments,
  # stays in comments ;-}
}

Usage:

var Hjson = require('hjson');

var obj = Hjson.parse(hjsonText);
var text2 = Hjson.stringify(obj);

Upvotes: 10

tarkh
tarkh

Reputation: 2549

There is alternative package on NPM: json-easy-strip The main idea is to use just one-liner RegExp to strip all type of JS-style comments. And yes, it's simple and very possible! Package is more advanced, with some file caching etc, but still simple. Here is the core:

sweet.json

{
    /*
     * Sweet section
     */
    "fruit": "Watermelon", // Yes, watermelons is sweet!
    "dessert": /* Yummy! */ "Cheesecake",
    // And finally
    "drink": "Milkshake - /* strawberry */ or // chocolate!" // Mmm...
}

index.js

const fs = require('fs');
const data = (fs.readFileSync('./sweet.json')).toString();

// Striper core intelligent RegExp.
// The idea is to match data in quotes and
// group JS-type comments, which is not in
// quotes. Then return nothing if there is
// a group, else return matched data.
const json = JSON.parse(data.replace(/\\"|"(?:\\"|[^"])*"|(\/\/.*|\/\*[\s\S]*?\*\/)/g, (m, g) => g ? "" : m));

console.log(json);

//  {
//    fruit: 'Watermelon',
//    dessert: 'Cheesecake',
//    drink: 'Milkshake - /* strawberry */ or // chocolate!'
//  }

So now because you was asking about ShellScripting-style comments

#
# comments
#

We can extend our RegExp by adding \#.* at the end of it:

const json = JSON.parse(data.replace(/\\"|"(?:\\"|[^"])*"|(\/\/.*|\/\*[\s\S]*?\*\/|\#.*)/g, (m, g) => g ? "" : m));

Or, if you don't want JS-style comments at all:

const json = JSON.parse(data.replace(/\\"|"(?:\\"|[^"])*"|(\#.*)/g, (m, g) => g ? "" : m));

Upvotes: 4

peteb
peteb

Reputation: 19428

You can use your own RegExp pretty easily to match the comments beginning with a #

const matchHashComment = new RegExp(/(#.*)/, 'gi');
const fs = require('fs');

fs.readFile('./file.json', (err, data) => {
    // replaces all hash comments & trim the resulting string
    let json = data.toString('utf8').replace(matchHashComment, '').trim();  
    json = JSON.parse(json);
    console.log(json);
});

Upvotes: 4

Kalman
Kalman

Reputation: 8121

The package you are looking for is called strip-json-comments - https://github.com/sindresorhus/strip-json-comments

const json = '{/*rainbows*/"unicorn":"cake"}';

JSON.parse(stripJsonComments(json)); //=> {unicorn: 'cake'}

Upvotes: 2

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