Moment.js Why do I get different Unix Timestamp values ​​with "same" input values?

Question

JavaScript

I have a simple code that implements the Timestamp API. It takes a date as input as a string MMMM-DD-YYYY or as a Unix Timestamp, converts and returns MMMM-DD-YYYY or Unix Timestamp respectively

var express = require('express');
var moment = require('moment');
var url = require('url');
var cors = require('cors');
var port = process.env.PORT || 8080;

var app = express();
app.use(cors());

app.route('/').get(function (req, res) {
    res.sendFile(process.cwd() + '/index.html')
});

app.get('/:date', function(req, res) {

    var URL = url.parse(req.url).pathname.replace(/%20/g, ' ').slice(1);

    if (isNaN(URL)) {
        var unixtime = moment(URL, "LL").unix()
        var naturaltime = moment(URL, "LL").format("LL")
    } else {
        var unixtime = moment.unix(URL, "LL").unix()
        var naturaltime = moment.unix(URL).format("LL")
    }

    res.send(JSON.stringify({
        unix : unixtime,
        natural : naturaltime
    }))

});

app.listen(port, function() {
    console.log('Node.js listening on port ' + port)
});

When I pass as request unix timestamp. e.g.
http://localhost:8080/1450137600
I get the following object in response

{
    unix: 1450137600,
    natural: "December 15, 2015"
}

But if I send for example the same December 15, 2015 I will
http://localhost:8080/December 15, 2015
get

{
    unix: 1450098000,
    natural: "December 15, 2015"
}

And
http://localhost:8080/1450098000

{
    unix: 1450098000,
    natural: "December 15, 2015"
}

Why do I get different unix timestamps for the same input values? Moreover, both timestamps indicate the same date December 15, 2015

Answer 1

UTC