Coordinates

Usage

import { DEFAULT_COORDINATE } from '@accelint/constants/coordinates';

// Initialize coordinate state
const [location, setLocation] = useState(DEFAULT_COORDINATE);

// Check for uninitialized coordinates
if (Number.isNaN(location[0]) || Number.isNaN(location[1])) {
  console.log('No location set');
}

Reference

const DEFAULT_COORDINATE: [number, number];

A tuple [Number.NaN, Number.NaN] representing an uninitialized or invalid coordinate.

Good to know: Using [0, 0] as a default is incorrect—it represents a real location in the Gulf of Guinea, off the west coast of Africa, known colloquially as "Null Island." Using NaN values explicitly indicates the absence of a valid coordinate.

Examples

Example: Initializing map state

import { DEFAULT_COORDINATE } from '@accelint/constants/coordinates';

interface MapState {
  center: [number, number];
  zoom: number;
}

const initialState: MapState = {
  center: DEFAULT_COORDINATE,
  zoom: 1,
};

Example: Validating coordinates

import { DEFAULT_COORDINATE } from '@accelint/constants/coordinates';

function isValidCoordinate(coord: [number, number]): boolean {
  return !Number.isNaN(coord[0]) && !Number.isNaN(coord[1]);
}

isValidCoordinate([40.7128, -74.0060]); // true (New York)
isValidCoordinate(DEFAULT_COORDINATE);   // false (uninitialized)
isValidCoordinate([0, 0]);               // true (Null Island - valid but unusual)

Example: Handling geolocation errors

import { DEFAULT_COORDINATE } from '@accelint/constants/coordinates';

function getCurrentLocation(): Promise<[number, number]> {
  return new Promise((resolve) => {
    if (!navigator.geolocation) {
      resolve(DEFAULT_COORDINATE);
      return;
    }

    navigator.geolocation.getCurrentPosition(
      (position) => {
        resolve([position.coords.latitude, position.coords.longitude]);
      },
      () => {
        resolve(DEFAULT_COORDINATE);
      },
    );
  });
}

Example: Conditional rendering based on coordinate validity

import { DEFAULT_COORDINATE } from '@accelint/constants/coordinates';

function LocationDisplay({ coords }: { coords: [number, number] }) {
  const isValid = !Number.isNaN(coords[0]) && !Number.isNaN(coords[1]);

  if (!isValid) {
    return <div>Location not available</div>;
  }

  return (
    <div>
      Latitude: {coords[0].toFixed(4)}, Longitude: {coords[1].toFixed(4)}
    </div>
  );
}

// Usage
<LocationDisplay coords={DEFAULT_COORDINATE} />
// Renders: "Location not available"

Example: Resetting coordinates

import { DEFAULT_COORDINATE } from '@accelint/constants/coordinates';

class LocationTracker {
  private location: [number, number] = DEFAULT_COORDINATE;

  setLocation(lat: number, lon: number): void {
    this.location = [lat, lon];
  }

  clearLocation(): void {
    this.location = DEFAULT_COORDINATE;
  }

  hasLocation(): boolean {
    return !Number.isNaN(this.location[0]) && !Number.isNaN(this.location[1]);
  }
}

Example: Type-safe coordinate handling

import { DEFAULT_COORDINATE } from '@accelint/constants/coordinates';

type Coordinate = [number, number];
type ValidCoordinate = [lat: number, lon: number];

function normalizeCoordinate(coord: Coordinate): ValidCoordinate | null {
  if (Number.isNaN(coord[0]) || Number.isNaN(coord[1])) {
    return null;
  }

  // Clamp latitude to [-90, 90]
  const lat = Math.max(-90, Math.min(90, coord[0]));
  // Normalize longitude to [-180, 180]
  const lon = ((coord[1] + 180) % 360) - 180;

  return [lat, lon];
}

normalizeCoordinate(DEFAULT_COORDINATE); // null
normalizeCoordinate([40.7128, -74.0060]); // [40.7128, -74.0060]

Null Island - Wikipedia article on the [0,0] coordinate
Geolocation API - MDN documentation

Coordinates

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