在NodeJS中使用JSON中的数据

Question

Hello i just started learning Nodejs and made a local server as a start then i saw that most nodejs apps have config and package files i couldnt find any info on how to do a simple one or use JSON files so i tried myself this is what i got so far

this is the server file

var http = require('http');
var json = require('./package');
var fs = require('fs');

var server = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello World\n');
}).listen(addr.port);

console.log('server listening at', addr.address + ':' + addr.port);

and this is the json file

{
    "addr": {
        "address":"http://127.0.0.1",
        "port":"8081"
    }
}

i know that it will work with json.address and json.port but when i added "addr" i thought it would simplify things with addr.port

so in short an explanation would be generously accepted on why it wont/shouldnt work or what im doing wrong

Answer 1

First of you should have a look at some tutorials or introduction sites like:

https://www.w3schools.com/nodejs/default.asp

Second: The package.json file is the main configuration file of your nodeJS application. Thats the config file that defines your start point of your application as well as all included modules. simply use npm init to create a default package.json file with basic information.

Third: If you require a json into your application as you did in your example the JSON is included hierarchically. Wich means The object you required has an attribute addr which itself is a new object with an attribute address .

So the correct way to access your information is json.addr.address based on your object description

you could also do something like this:

 var network = require('./settings').addr; console.log("ip => " + network.address); console.log("port => " + network.port); 

Answer 2

You need to list the parent object. You have put addr.address and addr.port, this means you are directly trying to access the addr object, but the this object doesn't exist. Try doing json.addr.address and json.addr.port and it should work.

var http = require('http');
var json = require('./package');
var fs = require('fs');

var server = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello World\n');
}).listen(json.addr.port);

console.log('server listening at', json.addr.address + ':' + json.addr.port);