How to blacklist locations (in a radius of 500 feet)

Question

EDIT: I have self-answered it below.

I have made a question on this before, however I could not properly set it up and the whole thing was broken. Below is the geolocation script. I would like to implement the blacklisting of certain areas (within a 500 foot radius if possible). Please explain to me how and where to make changes, as I am a beginner in JavaScript. thank you. (NOTE: No list or dictionary is on the page as it was part of my problem.)

current code:

if (navigator.geolocation) {
    // Locate position
    navigator.geolocation.getCurrentPosition(displayPosition, errorFunction);
} else {
    alert('It seems like Geolocation, which is required for this page, is not enabled in your browser. Please use a browser which supports it.');
}

// Success callback function
function displayPosition(pos) {
    var mylat = pos.coords.latitude;
    var mylong = pos.coords.longitude;
    var thediv = document.getElementById('locationinfo');
    thediv.innerHTML = '<p>Your longitude is :' +
        mylong + ' and your latitide is ' + mylat + '</p>';

// Error callback function
function errorFunction(pos) {
    alert('Error!');
}

Answer 1

given a blacklist structure as follows (as you refuse to share anything about the blacklist data you have)

var blacklistedCoordinates = [
    { longitude: 0, latitude: 0},
    { longitude: 1, latitude: 10},
    { longitude: 2, latitude: 20},
    { longitude: 3, latitude: 30},
    { longitude: 4, latitude: 40}
];

your code, modified

if (navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(displayPosition, errorFunction);
} else {
    alert('It seems like Geolocation, which is required for this page, is not enabled in your browser. Please use a browser which supports it.');
}

// Success callback function
function displayPosition(pos) {   
    var mylat = pos.coords.latitude;
    var mylong = pos.coords.longitude;
    var thediv = document.getElementById('locationinfo');
    thediv.innerHTML = '<p>Your longitude is :' + mylong + ' and your latitide is ' + mylat + '</p>';
    // additional code to output blacklist locations within 500ft
    blacklistedCoordinates
    .filter(black => calcCrow(black, pos.coords) < 500)
    .forEach(black => { // output blacklisted locations
        thediv.innerHTML = '<p>Blacklisted longitude is :' + black.longitude + ' and latitide is ' + black.latitude + '</p>';
    });
}
// Error callback function
function errorFunction(pos) {
    alert('Error!');
}

code from https://stackoverflow.com/a/28673693/5053002 - modified to return feet

function calcCrow(coords1, coords2) {
    const toRad = value => value * Math.PI / 180;
    const R = 20.90223164; // work in feet
    const dLat = toRad(coords2.latitude - coords1.latitude);
    const dLon = toRad(coords2.longitude - coords1.longitude);
    const lat1 = toRad(coords1.latitude);
    const lat2 = toRad(coords2.latitude);

    const a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2); 
    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
    const d = R * c;
    return d;
}

Answer 2

Thanks to Jaramoda for is awenser, it contributed to the final solution. First off, the code for calculated the radial coordinates was broken, I decided to replace it with the original and make changes so that it would work with my current code:

function calcCrow(coords1, coords2)
{
  // var R = 6.371; // km
  var R = 6371000;
  var dLat = toRad(coords2.latitude - coords1.latitude);
  var dLon = toRad(coords2.longitude - coords1.longitude);
  var lat1 = toRad(coords1.latitude);
  var lat2 = toRad(coords2.latitude);

  var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
    Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2); 
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
  var d = R * c;
  return d;
}

I attached it to the same area, and specified it for 250meters (270 yards?) I will of course need to tinker with the values for more ideal distances.

Next, I tested it without my coordinates in the dictionary, and it did not return anything (a good thing, this was the problem before). And then I entered coordinates and it worked just fine.

This took almost a day to figure out the source of the issue for me, though it seems quite obvious now xD