npm install json-format

  var jsonFormat = require('./');
  var fs = require('fs');
  var obj = {
    a: 1,
    b: 2
  }

  fs.writeFile('example.json', jsonFormat(obj), function(err){
    if (err) throw err;
    console.log('saved');
  });

{
  "a": 1,
  "b": 2
}