Displays a modal window temperature in KELVINS, how can I convert to Celsius, can someone tell me?

Question

JavaScript

I can't figure out how to convert the temperature to Kelvin, can someone tell me

<script>
    function initMap() {
        var map = new google.maps.Map(document.getElementById('map'), {
            zoom: 6,
            center: {lat: 49.00, lng: 32.00}
        });

        var modal = document.getElementById('modal'),
            res,
            markerCoord,
            marker,
            markersArray = [],
            infowindow,
            contentString,
            xmlhttp = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");

        google.maps.event.addListener(map, 'click', function (e) {

            markerCoord = {lat: e.latLng.lat(), lng: e.latLng.lng()};
            makeMarker();

            // Get ajax call to get weather info
            xmlhttp.onreadystatechange = function() {
                if (xmlhttp.readyState == XMLHttpRequest.DONE ) {
                    if (xmlhttp.status == 200) {
                        res = JSON.parse(xmlhttp.responseText);
                        openModal(res);
                    }
                    else if (xmlhttp.status == 400) {
                        console.log('There was an error 400');
                    }
                    else {
                        console.log('something else other than 200 was returned');
                    }
                }
            };

            xmlhttp.open("GET", "http://api.openweathermap.org/data/2.5/weather?lat=" + markerCoord.lat + "&lon=" + markerCoord.lng + '&apiKey=05d1a9582076e6fecf5c7a3a363b8328', true);
            xmlhttp.send();
        });

        // Make clear all old markers and add new one
        function makeMarker() {
            for (var i in markersArray) {
                markersArray[i].setMap(null);
            }
            markersArray.length = 0;

            marker = new google.maps.Marker({
                position: markerCoord,
                map: map,
                title: 'Weather here'
            });
            markersArray.push(marker);
        }

        function openModal(res) {
            contentString = '<div id="content">'+
                    '<div id="siteNotice">'+
                    '</div>'+
                    '<div><b>Place: </b><span id="place"> ' + res.name + '</span> </div>'+
                    '<p><b>Weather:</b> <span id="weather">' + res.weather[0].main + '</span></p>'+
                    '<p><b>Temp:</b> <span id="temp">' + res.main.temp +'</span>&#176 K</p>'+
                    '<p><b>Wind speed:</b> <span id="wind">' + res.wind.speed + '</span> ms</p>'+ 
                    '<p><b>Humidity:</b> <span id="humidity">' + res.main.humidity + '</span>%</p>'+ 
                    '</div>';

            infowindow = new google.maps.InfoWindow({
                content: contentString
            });

        </pre>    infowindow.open(map, marker);
        }
    }
</script>

Answer 1

Subtract 273 from Kelvin to get Celsius.

function openModal(res) {
            contentString = '<div id="content">'+
                    '<div id="siteNotice">'+
                    '</div>'+
                    '<div><b>Place: </b><span id="place"> ' + res.name + '</span> </div>'+
                    '<p><b>Weather:</b> <span id="weather">' + res.weather[0].main + '</span></p>'+
                    '<p><b>Temp:</b> <span id="temp">' + (res.main.temp - 273) +'</span>&#176 K</p>'+
                    '<p><b>Wind speed:</b> <span id="wind">' + res.wind.speed + '</span> ms</p>'+ 
                    '<p><b>Humidity:</b> <span id="humidity">' + res.main.humidity + '</span>%</p>'+ 
                    '</div>';

            infowindow = new google.maps.InfoWindow({
                content: contentString
            });

            infowindow.open(map, marker);
        }