在IONIC 2中使用Javascript API计算两点之间的距离

function calculateDistance(lat1, lon1, lat2, lon2) {
  const R = 6371; // 地球半径，单位为千米
  const dLat = toRadians(lat2 - lat1);
  const dLon = toRadians(lon2 - lon1);
  const a =
    Math.sin(dLat / 2) * Math.sin(dLat / 2) +
    Math.cos(toRadians(lat1)) * Math.cos(toRadians(lat2)) *
    Math.sin(dLon / 2) * Math.sin(dLon / 2);
  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  const distance = R * c; // 距离，单位为千米
  return distance;
}

function toRadians(degrees) {
  return degrees * Math.PI / 180;
}

// 示例用法
const distance = calculateDistance(40.7128, -74.0060, 34.0522, -118.2437);
console.log(distance); // 输出距离，单位为千米