How to delete a info with ID from JSON based data - json

Question

The content of my JSON file is:
This is my retails.json file.actually retails is my database.i converted this json file from sql database.so in this json file, I want to delete a person information with a single ID.How can i do? i am using node.js and express.
{
"categories" : [
{
"dept_id" : "123",
"category_name" : "database",
"category_discription" : "list of database",
"current time" : "2016-07-21 06:27:17",
"id" : "1"
},
{
"dept_id" : "1234",
"category_name" : "debugging",
"category_discription" : "program debugger",
"current time" : "2016-07-21 06:32:24",
"id": "2"
},
{
"dept_id" : "12345",
"category_name" : "system analyzer",
"category_discription" : null,
"current time" : "2016-07-21 06:33:23",
"id" : "3"
}
],
"departments" : [
{
"name" : "manpreet singh",
"address_info" : "qadian",
"current time" : null,
"id" : "1"
},
{
"name" : "tushal gupta",
"address_info" : "amritsar",
"current time" : "2016-07-21 06:10:14",
"id" : "2"
},
{
"name" : "haroop singh",
"address_info" : "amritsar",
"current time" : "2016-07-21 06:11:12",
"id" : "3"
}
],
"digital_marketing" : [
{
"dept_id" : "123",
"phone" : "99889988",
"mobile" : null,
"email" : "thbs#gmail.com",
"web" : null,
"facebook" : null,
"twitter" : null,
"linkedin" : null,
"current time" : "2016-07-21 06:10:16",
"id" : "1"
},
{
"dept_id" : "1234",
"phone" : "998899888",
"mobile" : null,
"email" : null,
"web" : null,
"facebook" : "gtudgal#fb.com",
"twitter" : "tushalgupta",
"linkedin" : null,
"current time" : "2016-07-21 06:30:19",
"id" : "2"
},
{
"dept_id" : "12345",
"phone" : "99889877",
"mobile" : null,
"email" : "fhdts#mail.com",
"web" : null,
"facebook":"sdfh33#fb.com",
"twitter" : null,
"linkedin" : null,
"current time" : "2016-07-21 06:30:13",
"id" : "3"
}
]
}
I am using this to delete a ID, but does not work:
var id = 2;
app.get('/deleteUser', function (req, res) {
// First read existing users.
fs.readFile( __dirname + "/" + "retails.json", 'utf8', function (err, data) {
data = JSON.parse( data );
delete data["categories" + 2];
console.log( data );
res.end( JSON.stringify(data));
});
});

Answer 1

for (var prop in jsonObj.categories){
delete jsonObj.categories[prop].id;
}
similar for digital_marketing etc. jsonObj is the data in your case..