CODEWITHSUNDEEP
javascriptnode.js
Conrad Scherb
Conrad Scherb

Reputation: 1056

JSON.parse(fs.readFileSync()) returning a buffer - string of numbers

I'm using a simple Node.js to pull information from a valid jsonfile (checked with JSLint), but the code i'm using doesn't return the expected value:

        squadJSON = JSON.parse(fs.readFileSync('./squads/squad' + whichSquad + '.json'));

and it returns:

{ type: 'Buffer', data: 
[ 123,
 10,
 32,
 32,
 34,
 97,
 99,
 ... 548 more items ] }

Any reason as to why this happens?

Upvotes: 88

Views: 105239

Answers (2)

Patrick Roberts
Patrick Roberts

Reputation: 51886

The "why" has been answered by Sidney, but a better "what to do" would be to use require(), which supports parsing valid JSON files synchronously and returning the result as an object:

squadJSON = require('./squads/squad' + whichSquad + '.json');

or even nicer, using an ES6 template literal:

squadJSON = require(`./squads/squad${whichSquad}.json`);

One notable difference using require() is that it resolves relative paths from __dirname, which is the directory path of the current module, whereas fs methods resolve relative paths using process.cwd(), or "current working directory". It is the directory within a shell session from which the main module of the program is executed by node.

Hopefully the examples below demonstrate how their relative path resolution differs:

To make require(...) behave like JSON.parse(fs.readFileSync(..., 'utf8')):

const { resolve } = require('path');

function readFileSyncJson (path) {
  return require(resolve(process.cwd(), path));
}

And to make JSON.parse(fs.readFileSync(..., 'utf8')) behave like require(...):

const { resolve } = require('path');

function requireJson (path) {
  return JSON.parse(fs.readFileSync(resolve(__dirname, path), 'utf8'));
}

Upvotes: 12

Sidney
Sidney

Reputation: 4775

fs.readFileSync() returns a Buffer if you don't specify an encoding.

https://nodejs.org/api/fs.html#fs_fs_readfilesync_path_options

So, tell fs.readFileSync() what encoding to use:

squadJSON = JSON.parse(fs.readFileSync('./squads/squad' + whichSquad + '.json', 'utf8'));

Upvotes: 192

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