Get coordinates, measure distances, and compare them

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1

I was proposed to develop a page where it presents an excerpt of Google Maps with several markers organized in clusters (done). I have no experience with JavaScript, and what I need is that by clicking a button (or not), it's possible to get my location and automatically be told which point on the map is closest to me.

Can someone help me? 

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 13,
    center: {
      lat: 40.963308,
      lng: -8.594651
    }
  });

  // Create an array of alphabetical characters used to label the markers.
  var labels = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

  // Add some markers to the map.
  // Note: The code uses the JavaScript Array.prototype.map() method to
  // create an array of markers based on a given "locations" array.
  // The map() method here has nothing to do with the Google Maps API.
  var markers = locations.map(function(location, i) {
    return new google.maps.Marker({
      position: location,
      label: labels[i % labels.length]
    });
  });

  // Add a marker clusterer to manage the markers.
  var markerCluster = new MarkerClusterer(map, markers, {
    imagePath: 'https://developers.google.com/maps/documentation/javascript/examples/markerclusterer/m'
  });
}

var locations = [{
    lat: 40.962157,
    lng: -8.593313
  },
  {
    lat: 40.962149,
    lng: -8.595695
  },
  {
    lat: 40.960351,
    lng: -8.598922
  },
  {
    lat: 40.967305,
    lng: -8.591450
  },
  {
    lat: 40.961682,
    lng: -8.608136
  }
]
    
asked by anonymous 18.10.2017 / 13:44

1 answer

1

I did a logic to get you to calculate the distance, and this way you can know which is the closest and get the latitude and longitude from this to show on the map. 

let atual = [-23.573037, -46.650190]
function calc(lat1, lon1, lat2, lon2){
        let R = 6371
	let dLat = (lat2 - lat1) * (Math.PI / 180)
	let dLon = (lon2 - lon1) * (Math.PI / 180)

	let a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(lat1 * (Math.PI / 180)) * Math.cos(lat2 * (Math.PI / 180)) * Math.sin(dLon / 2) * Math.sin(dLon / 2)
	let c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))
	let d = R * c

	return d
}

function getGeo(position){
	alert('A distancia entre os prontos é de: ' + calc(position.coords.latitude, position.coords.longitude, atual[0], atual[1]))
}

function error() {
	alert("Erro")
}

let options = {
	enableHighAccuracy: true, 
	maximumAge        : 30000, 
	timeout           : 27000
}

let wpid = navigator.geolocation.watchPosition(getGeo, error, options)

Just adapt in the way that best suits you;)

    
18.10.2017 / 15:10
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