google.maps.geometry.spherical.computeDistanceBetween(from, to)

// 初始化地图
function initMap() {
  const map = new google.maps.Map(document.getElementById("map"), {
    center: { lat: 34.0522, lng: -118.2437 }, // 洛杉矶
    zoom: 8,
  });
  
  // 定义两个点
  const point1 = new google.maps.LatLng(34.0522, -118.2437); // 洛杉矶
  const point2 = new google.maps.LatLng(40.7128, -74.0060);  // 纽约
  
  // 计算距离（米）
  const distanceInMeters = google.maps.geometry.spherical.computeDistanceBetween(point1, point2);
  
  // 转换为千米
  const distanceInKm = distanceInMeters / 1000;
  
  console.log("距离: " + distanceInMeters + " 米");
  console.log("距离: " + distanceInKm + " 千米");
  
  // 在地图上显示标记和距离
  new google.maps.Marker({ position: point1, map: map, title: "洛杉矶" });
  new google.maps.Marker({ position: point2, map: map, title: "纽约" });
  
  const infoWindow = new google.maps.InfoWindow({
    content: "洛杉矶到纽约的距离: " + distanceInKm.toFixed(2) + " 千米",
    position: { lat: 37.5, lng: -96.0 }
  });
  
  infoWindow.open(map);
}

<script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry"></script>