How to Parse JSON Using Node.Js

How to parse JSON using Node.js?

You can simply use JSON.parse.

The definition of the JSON object is part of the ECMAScript 5 specification. node.js is built on Google Chrome's V8 engine, which adheres to ECMA standard. Therefore, node.js also has a global object JSON^[docs].

Note - JSON.parse can tie up the current thread because it is a synchronous method. So if you are planning to parse big JSON objects use a streaming json parser.

How to parse JSON in node js

User is already a list of objects, so you don't need to parse it. However, it is an array. So if you meant for it to be an array, you'd need to access the password by using this code:

console.log(user[0].password);

Parse json data seperated by new line in Nodejs

If I understand correctly, the data is not a valid JSON string, but rather JSON strings separated by line breaks. So this is how the data can be converted into the array of objects with sorted key order:

'use strict';
const data =`{"response": "True", "controllerId": "2751", "level": "INFO", "logType": "watchdogResponse", "deviceId": "2751", "container": "firmware", "epoch": "1549996256", "module": "hostServices", "ts": "2019-02-13 00:00:56"}{"ts": "2019-02-13 00:01:10", "epoch": "1549996270", "level": "INFO", "module": "jr", "logType": "running", "controllerId": "2751", "deviceId": "2751", "rid": "EXTERNAL CALL", "val": "1549996260000"}{"ts": "2019-02-13 00:01:10", "epoch": "1549996270", "level": "INFO", "module": "applicationMain", "logType": "wifi", "controllerId": "2751", "deviceId": "2751", "networkStrength": "100.0"}`;
const sortedArrayOfObjects = data  .split('\n')  .map(JSON.parse)  .map(obj => Object.entries(obj).sort().reduce(    (o, [k, v]) => (o[k] = v, o), {})  );
console.log(sortedArrayOfObjects);

Parse json response in nodejs

Please try this:

var data=response[0].credentials;
for (var i=0; i<data.length; i++){
  console.log(data[i]._id);
  console.log(data[i].username);
}

Here is jsfiddle

Using Node.JS, how do I read a JSON file into (server) memory?

Sync:

var fs = require('fs');
var obj = JSON.parse(fs.readFileSync('file', 'utf8'));

Async:

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

How to parse JSON in node js

User is already a list of objects, so you don't need to parse it. However, it is an array. So if you meant for it to be an array, you'd need to access the password by using this code:

console.log(user[0].password);

How to parse JSON with escaped doublequotes, using node.js?

Since that part of the data is JSON-within-JSON, you'd parse the JSON, then parse the JSON on the attributes property:

const obj = JSON.parse(json);
obj.attributes = JSON.parse(obj.attributes);

Live Example:

const json = document.getElementById("json").textContent;

const obj = JSON.parse(json);
obj.attributes = JSON.parse(obj.attributes);
console.log(obj);

<pre id="json">{
    "name": "John",
    "attributes": "{\"key\":\"value\"}"
}</pre>

NodeJs JSON parsing issue

don't use JSON.stringify as it is further changing the string representation of JSON object. An example of what is happening is below

Imagine if you have a data in your file as shown below

{
   "key": "value"
}

When you read the file (using readFileSync) and apply JSON.stringify, it is converted to a new string as shown below. You can notice that the double quotes are now escaped

"{\"key\": \"value\"}"

Now when you will parse it using JSON.parse then instead of getting the desired object, you are going to get back the same string you read from the file.

You are basically first performing and then undoing the stringify operation

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