Using google maps API, how can we set the current location as the default set location using map.setCenter function?_问答_开发者

I am writing JavaScript code using Google Maps API.

map = new google.maps.Map2(document.getElementById("map_canvas"));
map.setCenter(new google.maps.LatLng(37.4419, -122.1419), 13);

The above code sets the default location of the map canvas to Palo Alto.

How can we write the script in such a way that the setCenter function automaticall开发者_如何学运维y points to the current location of the client?

You can use the HTML5 GeoLocation API in browsers that support it.

if (navigator.geolocation) {
  navigator.geolocation.getCurrentPosition(success, error);
} else {
  alert('geolocation not supported');
}

function success(position) {
  alert(position.coords.latitude + ', ' + position.coords.longitude);
}

function error(msg) {
  alert('error: ' + msg);
}

I can think of two possible options.

First you may want to consider using the GeoLocation API as ceejayoz suggested. This is very easy to implement, and it is a fully client-side solution. To center the map using GeoLocation, simply use:

map.setCenter(new google.maps.LatLng(position.coords.latitude, 
                                     position.coords.longitude), 13);

... inside the success() callback of the GeoLocation's getCurrentPosition() method.

Unfortunately only a few modern browsers are currently supporting the GeoLocation API. Therefore you can also consider using a server-side solution to resolve the IP address of the client into the user's location, using a service such as MaxMind's GeoLite City. Then you can simply geocode the city and country of the user inside the browser, using the Google Maps API. The following could be a brief example:

<!DOCTYPE html>
<html> 
<head> 
    <meta http-equiv="content-type" content="text/html; charset=UTF-8"/> 
    <title>Google Maps API Geocoding Demo</title> 
    <script src="http://maps.google.com/maps?file=api&amp;v=2&amp;sensor=false"
            type="text/javascript"></script> 
  </head> 
  <body onunload="GUnload()"> 

    <div id="map_canvas" style="width: 400px; height: 300px"></div> 

    <script type="text/javascript"> 

    var userLocation = 'London, UK';

    if (GBrowserIsCompatible()) {
       var geocoder = new GClientGeocoder();
       geocoder.getLocations(userLocation, function (locations) {         
          if (locations.Placemark) {
             var north = locations.Placemark[0].ExtendedData.LatLonBox.north;
             var south = locations.Placemark[0].ExtendedData.LatLonBox.south;
             var east  = locations.Placemark[0].ExtendedData.LatLonBox.east;
             var west  = locations.Placemark[0].ExtendedData.LatLonBox.west;

             var bounds = new GLatLngBounds(new GLatLng(south, west), 
                                            new GLatLng(north, east));

             var map = new GMap2(document.getElementById("map_canvas"));

             map.setCenter(bounds.getCenter(), map.getBoundsZoomLevel(bounds));
             map.addOverlay(new GMarker(bounds.getCenter()));
          }
       });
    }
    </script> 
  </body> 
</html>

Simply replace userLocation = 'London, UK' with the server-side resolved address. The following is a screenshot from the above example:

Using google maps API, how can we set the current location as the default set location using map.setCenter function?

You can remove the marker by getting rid of the map.addOverlay(new GMarker(bounds.getCenter())); line.

that already exists in the google api:

if (GBrowserIsCompatible()) 
{   
    var map = new google.maps.Map2(document.getElementById("mapdiv"));

    if (google.loader.ClientLocation) 
    {        
        var center = new google.maps.LatLng(
            google.loader.ClientLocation.latitude,
            google.loader.ClientLocation.longitude
        );
        var zoom = 8;

        map.setCenter(center, zoom);
    }
}

There are several threads with the same question...

This solution tries to get user location from browser first, if the user refused or any other error occurs it then gets the location from user's IP address

mapUserLocation = () => {
  navigator.geolocation
    ? navigator.geolocation.getCurrentPosition(
        handlePosition,
        getLocationFromIP
      )
    : getLocationFromIP();
};

getLocationFromIP = () => {
  fetch("http://ip-api.com/json")
    .then(response => response.json())
    .then(data => {
      data.lat &&
        data.lon &&
        updateUserPosition({
          lat: data.lat,
          lng: data.lon
        });
    })
    .catch(error => {
      console.log(`Request failed: `, error);
    });
};

handlePosition = position => {
  const userPos = {
    lat: position.coords.latitude,
    lng: position.coords.longitude
  };
  updateUserPosition(userPos);
};

updateUserPosition = position => {
  map.setCenter(position, 13);
};

and call it like:

mapUserLocation();

An updated version of @ceejayoz's answer:

    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(success, error);
    } else {
        alert('geolocation not supported');
    }
    function error(msg) {
        alert('error: ' + msg);
    }
    function success(position) {

        var myLatlng = new google.maps.LatLng(position.coords.latitude, position.coords.longitude);
        var mapOptions = {
            zoom: 12,
            center: myLatlng,
            scaleControl: false,
            draggable: false,
            scrollwheel: false,
            navigationControl: false,
            mapTypeControl: false
        }


        map = new google.maps.Map(document.getElementsByClassName('map-canvas')[0], mapOptions);
        marker = new google.maps.Marker({
            position: myLatlng,
            map: map,
            title: 'Main map',
            icon: iconBase + 'arrow.png'
        });
    }

map = new google.maps.Map2(document.getElementById("map_canvas"));
pos = new google.maps.LatLng(37.4419, -122.1419);
map.setCenter(pos, 13);
map.panTo(pos);

Try this bro : I centered Indonesia using lat and lng.

$(document).ready(function () {
    var mapOptions = {
        zoom: 4,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };

    var map = new google.maps.Map(document.getElementById('map'), mapOptions);
    
    var center = new google.maps.LatLng(-2.548926, 118.0148634);
    map.setCenter(center,4);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="http://maps.googleapis.com/maps/api/js?libraries=places&sensor=false"></script>

<div id="map" style="width:600px; height:450px"></div>