index.js

var express = require('express')
const timezone = require("./timezone");

var app = express()

app.set('port', (process.env.PORT || 5000))
app.use(express.static(__dirname + '/public'))

app.get('/', function(request, response) {
  
 response.send('You are on home page');

})

app.get('/dateTimeConversion', function (req, res) {
  
  var body = {};
  try{
    var dateTime = req.query.dateTime;
    var convertTo = req.query.convertTo;
    var convertFrom = req != null && req != 'undefined' && req.query != null && req.query != 'undefined' && req.query.convertFrom != null && req.query.convertFrom != null ? req.query.convertFrom : null;
    var utcOffset = convertTo != null && (convertTo == 'undefined' || convertTo.toLocaleLowerCase() == 'utc') ? "+00:00" : null ;   // by default

    if(dateTime != null && dateTime != 'undefined' && convertTo != null && convertTo != 'undefined' && convertTo.toLocaleLowerCase() != 'utc'){
      
      //Check timezone.JSON file tzCode to get offset value.
      timezone.forEach(element => {
        
         if(element.tzCode != null && element.tzCode != 'undefined' && element.tzCode == convertTo){
            if(element.offset != null && element.offset != 'undefined'){
              utcOffset = element.offset ;
            }
         }
      });

      if(utcOffset == null){
        body["success"] = false;
        body["message"] = "Bad value for convertTo param. Use only GMT or UTC.";
      }else{
        //Split the offset fetched into hours and minutes.
        var a = utcOffset.split(':');
        var hour = +a[0];
        var minute = utcOffset[0] == '-' ? -1 * +a[1] : +a[1] ;

        //Get the value in minutes for the offset.
        var tzDifference = hour * 60 + minute;

        var targetTime = new Date(dateTime);

        //get the date in convertTo timezone.
        targetTime = new Date(targetTime.getTime() + ( tzDifference * 60 * 1000));

        //get the am/pm format time from the targetTime.
        var hours = targetTime.getHours();
        var minutes = targetTime.getMinutes();
        var ampm = hours >= 12 ? 'pm' : 'am';
        hours = hours % 12;
        hours = hours ? hours : 12; // the hour '0' should be '12'
        minutes = minutes < 10 ? '0'+minutes : minutes;
        var strTime = hours + ':' + minutes + ' ' + ampm;

        body["success"] = true;
        body["date"] = targetTime.getFullYear() + "-" + ( (targetTime.getMonth()+1) < 10 ? '0'+(targetTime.getMonth()+1) : (targetTime.getMonth()+1))
                       + "-" + ( targetTime.getDate() < 10 ? '0'+targetTime.getDate() : targetTime.getDate()) ;     //// date in YYYY-MM-DD format
        body["time"] = strTime;
        body["dateTime"] = targetTime.toISOString();
      }

    }else if(dateTime != null && dateTime != 'undefined' && convertTo != null && convertTo != 'undefined' && convertTo.toLocaleLowerCase() == 'utc' && 
            convertFrom != null && convertFrom != 'undefined'){
      
      //Check timezone.JSON file tzCode to get offset value.
      timezone.forEach(element => {
        
         if(element.tzCode != null && element.tzCode != 'undefined' && element.tzCode == convertFrom){
            if(element.offset != null && element.offset != 'undefined'){
              utcOffset = element.offset ;
            }
         }
      });

      //Split the offset fetched into hours and minutes.
      var a = utcOffset.split(':');
      var hour = +a[0];
      var minute = utcOffset[0] == '-' ? -1 * +a[1] : +a[1] ;

      //Get the value in minutes for the offset.
      var tzDifference = hour * 60 + minute;

      var targetTime = new Date(dateTime);
     
      //get the date in convertFrom timezone.
      targetTime = new Date(targetTime.getTime() - ( tzDifference * 60 * 1000));

      //get the am/pm format time from the targetTime.
      var hours = targetTime.getHours();
      var minutes = targetTime.getMinutes();
      var ampm = hours >= 12 ? 'pm' : 'am';
      hours = hours % 12;
      hours = hours ? hours : 12; // the hour '0' should be '12'
      minutes = minutes < 10 ? '0'+minutes : minutes;
      var strTime = hours + ':' + minutes + ' ' + ampm;

      body["success"] = true;
      body["date"] = targetTime.getFullYear() + "-" + ( (targetTime.getMonth()+1) < 10 ? '0'+(targetTime.getMonth()+1) : (targetTime.getMonth()+1))
                     + "-" + ( targetTime.getDate() < 10 ? '0'+targetTime.getDate() : targetTime.getDate()) ;     //// date in YYYY-MM-DD format
      body["time"] = strTime;
      body["dateTime"] = targetTime.toISOString();
         
     }else{

      body["success"] = false;
      body["message"] = "Required field missing or Date not in proper ISO format.";

    }
  
  }catch (exception) {
    body["success"] = false;
    body["message"] = exception;
    console.log(exception)
  }
  finally {
    res.send(body);
  }
})


app.get('/getCurrentDateTime', function (req, res) {
  
  var body = {};
  try{
    var dateTime = new Date();
    var convertTo = req.query.convertTo;
    var utcOffset = convertTo != null && (convertTo == 'undefined' || convertTo.toLocaleLowerCase() == 'utc') ? "+00:00" : null ;   // by default

    if(dateTime != null && dateTime != 'undefined' ){
      
      if(convertTo != null && convertTo != 'undefined'){
        //Check timezone.JSON file tzCode to get offset value.
        timezone.forEach(element => {

           if(element.tzCode != null && element.tzCode != 'undefined' && element.tzCode == convertTo){
              if(element.offset != null && element.offset != 'undefined'){
                utcOffset = element.offset ;
              }
           }
        });
      }

      if(utcOffset == null){
        body["success"] = false;
        body["message"] = "Bad value for convertTo param. Use only GMT or UTC.";
      }else{
        //Split the offset fetched into hours and minutes.
        var a = utcOffset.split(':');
        var hour = +a[0];
        var minute = utcOffset[0] == '-' ? -1 * +a[1] : +a[1] ;

        //Get the value in minutes for the offset.
        var tzDifference = hour * 60 + minute;

        var targetTime = new Date(dateTime);

        //get the date in convertTo timezone.
        targetTime = new Date(targetTime.getTime() + ( tzDifference * 60 * 1000));

        //get the am/pm format time from the targetTime.
        var hours = targetTime.getHours();
        var minutes = targetTime.getMinutes();
        var ampm = hours >= 12 ? 'pm' : 'am';
        hours = hours % 12;
        hours = hours ? hours : 12; // the hour '0' should be '12'
        minutes = minutes < 10 ? '0'+minutes : minutes;
        var strTime = hours + ':' + minutes + ' ' + ampm;


        body["success"] = true;
        body["date"] = targetTime.getFullYear() + "-" + ( (targetTime.getMonth()+1) < 10 ? '0'+(targetTime.getMonth()+1) : (targetTime.getMonth()+1))
                       + "-" + ( targetTime.getDate() < 10 ? '0'+targetTime.getDate() : targetTime.getDate()) ;     //// date in YYYY-MM-DD format
        body["time"] = strTime;
        body["dateTime"] = targetTime.toISOString();
      }

    }else{

      body["success"] = false;
      body["message"] = "Required field missing or Date not in proper ISO format.";

    }
  
  }catch (exception) {
    body["success"] = false;
    body["message"] = exception;
  }
  finally {
    res.send(body);
  }
})

app.listen(app.get('port'), function() {
  console.log("Node app is running at localhost:" + app.get('port'))
})