Reading Json files using Node.js

Question

I have the following node.js file:

[
  {
    "name":"Apple inc",
    "symbol":"AAPL",
    "logo":"apple.png",    
    "price":123,
    "prod":"Apple inc, mac, macbook, iphone, ipod, ipad, osx"
  },
  {
    "name":"Nvidia Corporation",
    "symbol":"NVDA",  
    "logo":"nvidia.png",
    "price":321,
    "prod":"Nvidia Corporation, gforce, g-force, shield"
  },
  {
    "name":"Google inc",
    "symbol":"GOOG", 
    "logo":"google.png",
    "price":321,
    "prod":"search, android, glass, drive, code school"
  }  
]

How can i access each object inside without the the index of the array, using only the symbol. Today i have a for loop that is running through all the array:

var fs = require('fs');

var stocks = JSON.parse(fs.readFileSync("stocks.json"));
for (var i=0; i<stocks.length; i++) {
    if (stocks[i].symbol==="GOOG") {
        console.log(i+ " ." , stocks[i] );

}

If i'll change the Json file to this format :

{ "APPL":
  {
    "name":"Apple inc",
    "symbol":"AAPL",
    "logo":"apple.png",    
    "price":123,
    "prod":"Apple inc, mac, macbook, iphone, ipod, ipad, osx"
  },
  "NVDA":
  {
    "name":"Nvidia Corporation",
    "symbol":"NVDA",  
    "logo":"nvidia.png",
    "price":321,
    "prod":"Nvidia Corporation, gforce, g-force, shield"
  },
  "GOOG":
  {
    "name":"Google inc",
    "symbol":"GOOG", 
    "logo":"google.png",
    "price":321,
    "prod":"search, android, glass, drive, code school"
  }  
}

Prabhu Murthy · Accepted Answer · 2014-09-01 09:06:26Z

1

you can use a simple for loop to iterate through

var obj = { "APPL":
  {
    "name":"Apple inc",
    "symbol":"AAPL",
    "logo":"apple.png",    
    "price":123,
    "prod":"Apple inc, mac, macbook, iphone, ipod, ipad, osx"
  },
  "NVDA":
  {
    "name":"Nvidia Corporation",
    "symbol":"NVDA",  
    "logo":"nvidia.png",
    "price":321,
    "prod":"Nvidia Corporation, gforce, g-force, shield"
  },
  "GOOG":
  {
    "name":"Google inc",
    "symbol":"GOOG", 
    "logo":"google.png",
    "price":321,
    "prod":"search, android, glass, drive, code school"
  }  
};

for(var i=0, keys = Object.keys(obj),len=keys.length; i <len ; i++){
  if(obj[keys[i]].symbol === "GOOG"){
    console.log(i +'.' +obj[keys[i]]);
  }
}

Object.keys(obj) will return ["APPL", "NVDA", "GOOG"]

to check if GOOG exists, you can do this

var result = Object.keys(obj).indexOf('GOOG') > -1;
console.log(result); // will be true

DEMO

edited Sep 1, 2014 at 9:06

answered Sep 1, 2014 at 7:38

Prabhu Murthy

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2 Comments

Alex Brodov Over a year ago

How can i check if the key is existing in stocks for example i want to check if IBM is there, should i just do t like this : if (stocks["IBM"!=null) another thing once i've updated the stocks how can i write it back to the file?

Prabhu Murthy Over a year ago

keys is an array, so if you want to check a item exists in it.you could do keys.indexOf('IBM') > -1

cillierscharl · Accepted Answer · 2014-09-01 07:50:16Z

1

If I'm understanding correctly, you'll be using the second format going forward?

That makes it as simple as :

var stocks = JSON.parse(fs.readFileSync("stocks.json"));
var goog = stocks.GOOG;

console.log(goog);

Otherwise you could query the original array if you wanted to:

var stocks = JSON.parse(fs.readFileSync("stocks.json"));
var goog = stocks.filter(function(stock) { if(stock.symbol == 'AAPL') return true; } );

console.log(goog[0]);

PS. don't use readFileSync it's really bad practice. ;)

edited Sep 1, 2014 at 7:50

answered Sep 1, 2014 at 7:39

cillierscharl

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