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The locationCheck.ts utility provides functions for determining whether a website visitor is located near Lake Ozark, Missouri. This is used to conditionally display location-specific content and features throughout the site.

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Overview

This utility uses geolocation data to identify visitors within approximately 50 miles of Lake Ozark Christian Church. It checks multiple criteria including:
  • Known local cities and counties
  • Distance calculation using the Haversine formula
  • Geographic coordinates (latitude/longitude)
File location: ~/workspace/source/src/utils/locationCheck.ts

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Exported Functions

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isLocalVisitor()

Determines if the current visitor is local to Lake Ozark area.
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Returns
Promise<boolean>
Returns true if visitor is local, false otherwise
Example usage: 
import { isLocalVisitor } from '../utils/locationCheck';

const isLocal = await isLocalVisitor();

if (isLocal) {
  // Show local-specific content
}
Real usage from index.astro: 
import { isLocalVisitor } from '../utils/locationCheck';

// This page uses server-side rendering for location checking
export const prerender = false;

let isLocal = false;
try {
  isLocal = await isLocalVisitor();
} catch (error) {
  console.warn('Location check failed, defaulting to non-local:', error);
  isLocal = false;
}

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getVisitorInfo()

Retrieves detailed information about the visitor’s location, including whether they are local and the reason for the determination.
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Returns
Promise<VisitorInfo>
Object containing location details:
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isLocal
boolean
Whether the visitor is considered local
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distance
number
Distance in miles from Lake Ozark (if coordinates available)
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reason
string
Explanation for the local/non-local determination
Example usage: 
import { getVisitorInfo } from '../utils/locationCheck';

const info = await getVisitorInfo();
console.log(`Is local: ${info.isLocal}`);
console.log(`Reason: ${info.reason}`);

if (info.distance) {
  console.log(`Distance: ${info.distance} miles`);
}
Real usage from Footer.astro: 
import { getVisitorInfo } from '../utils/locationCheck';

const info = await getVisitorInfo();
const isLocal = info.isLocal;

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Local Area Definition

The utility defines the local area using several constants:

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LOCAL_CITIES

Array of cities within approximately 50 miles of Lake Ozark: 
export const LOCAL_CITIES = [
  // Lake Area Core
  'Lake Ozark', 'Osage Beach', 'Camdenton', 'Sunrise Beach',
  'Village of Four Seasons', 'Rocky Mount', 'Lakeside',
  'Linn Creek', 'Eldon', 'Kaiser', 'Laurie', 'Versailles',
  'Gravois Mills', 'Stover', 'Tuscumbia',
  
  // Nearby Cities
  'Lebanon', 'Richland', 'Iberia', 'Brumley', 'Montreal',
  'Climax Springs', 'Macks Creek', 'Barnett', 'Cole Camp',
  'Lincoln', 'Warsaw', 'Edwards', 'Fortuna', 'California', 'Tipton',
];

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LOCAL_COUNTIES

Array of counties considered local to Lake Ozark: 
export const LOCAL_COUNTIES = [
  'Camden', 'Miller', 'Morgan', 'Benton', 'Laclede',
  'Pulaski', 'Cole', 'Moniteau', 'Cooper', 'Pettis',
];

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How It Works

The location check follows this logic:
  1. Fetch geolocation data from https://geo.locc.us/where (5-second timeout)
  2. Check country: If not in the US, return isLocal: false
  3. For Missouri visitors:
    • Check if city matches LOCAL_CITIES array
    • Check if county matches LOCAL_COUNTIES array
    • Calculate distance using coordinates (Haversine formula)
    • Return isLocal: true if within 50 miles
  4. Out-of-state visitors: Return isLocal: false
  5. On error or timeout: Return isLocal: false with appropriate reason

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Distance Calculation

The utility uses the Haversine formula to calculate distance between two geographic points: 
function calculateDistance(
  lat1: number, lon1: number,
  lat2: number, lon2: number
): number {
  const R = 3959; // Earth's radius in miles
  // ... Haversine formula implementation
  return R * c; // Distance in miles
}
Lake Ozark coordinates:
  • Latitude: 38.1981839
  • Longitude: -92.6386717

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TypeScript Interfaces

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GeoResponse

Response from the geolocation API: 
interface GeoResponse {
  country_code: string;
  country_name: string;
  region: string;
  city: string;
  county?: string;
  latitude: string;
  longitude: string;
  ip: string;
  gdpr: boolean;
  cpa: boolean;
  lgpd: boolean;
  pipeda: boolean;
  appa: boolean;
  language: string;
  timezone: string;
  asn: number;
}

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VisitorInfo

Returned by getVisitorInfo(): 
interface VisitorInfo {
  isLocal: boolean;
  distance?: number;
  reason: string;
}

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Server-Side Rendering Required

Pages using location check utilities must use server-side rendering: 
// Disable prerendering to enable SSR
export const prerender = false;

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Error Handling

The utility includes comprehensive error handling:
  • API request failures: Returns isLocal: false with reason “API request failed”
  • Timeout (5 seconds): Returns isLocal: false with reason “Location check timed out”
  • Other errors: Returns isLocal: false with error message in reason
Best practice: 
let isLocal = false;
try {
  isLocal = await isLocalVisitor();
} catch (error) {
  console.warn('Location check failed:', error);
  isLocal = false; // Safe default
}

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Usage Examples

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Conditional Content Display

import { isLocalVisitor } from '../utils/locationCheck';

const isLocal = await isLocalVisitor();

{isLocal && (
  <section class="local-events">
    <h2>Events Near You</h2>
    <!-- Local-specific content -->
  </section>
)}

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Debug Information

import { getVisitorInfo } from '../utils/locationCheck';

const info = await getVisitorInfo();
console.log('Visitor Info:', info);
// Example output:
// {
//   isLocal: true,
//   distance: 12.5,
//   reason: "Within 50 miles of Lake Ozark (13 miles)"
// }

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Pages Using This Utility

  • src/pages/index.astro - Homepage local content
  • src/pages/worship.astro - Worship page location features
  • src/pages/children-youth.astro - Children & youth page
  • src/ui/Footer.astro - Footer location-based content

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Dependencies

  • Geolocation API: https://geo.locc.us/where
  • Fetch API: Built-in browser/Node.js fetch
  • AbortController: For request timeout handling

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