Haversine Calculator

This is a simple module to help you determine the great-circle distance between two points on a sphere given their longitudes and latitudes o a geojson file.

The formula

This uses the ‘haversine’ formula to calculate the great-circle distance between two points – that is, the shortest distance over the earth’s surface – giving an ‘as-the-crow-flies’ distance between the points (ignoring any hills they fly over, of course!).

Haversine: a = sin²(Δφ/2) + cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2) c

formula: c = 2 ⋅ atan2( √a, √(1−a) ) d = R ⋅ c

where φ is latitude, λ is longitude, R is earth’s radius (mean radius = 6,371km); The angles need to be in radians to pass to trig functions.

Installation

`$ npm install haversine-calculator

Usage of this module

haversine (start, end, options)

const haversineCalculator = require('haversine-calculator')

const start = {
  latitude: -23.754842,
  longitude: -46.676781
}

const end = {
  latitude: -23.549588,
  longitude: -46.693210
}

console.log(haversineCalculator(start, end))
console.log(haversineCalculator(start, end, {unit: 'meter'}))
console.log(haversineCalculator(start, end, {unit: 'mile'}))
console.log(haversineCalculator(start, end, {threshold: 1}))
console.log(haversineCalculator(start, end, {threshold: 1, unit: 'meter'}))
console.log(haversineCalculator(start, end, {threshold: 1, unit: 'mile'}))

The api

• options.unit - Unit of measurement applied to result (default km, available km, mile, meter, nmi)
• options.threshold - If passed, will result in library returning boolean value of whether or not the start and end points are within that supplied threshold. (default null)
• options.format - The format of start and end coordinate arguments. See the table below for available values. (default null)

Format	Example
undefined (default)	{ latitude: -23.754842, longitude: -46.676781] }
[lat,lon]	[-23.754842, -46.676781]
[lon,lat]	[-23.754842, -46.676781]
{lat,lon}	{ lat: -23.754842, lon: -46.676781] }
geojson	{ type: 'Feature', geometry: { coordinates: [-23.754842, -46.676781] } }

MIT License