buffer-point.js

#!/usr/bin/env node

var turf = require('turf');

function usage() {
  console.log('Usage: ./buffer-point [lat] [lng] [distance]\n');
}

process.argv.shift();
process.argv.shift();
if (process.argv.length !== 3) {
  usage();
  process.exit(1);
}

var lat = process.argv.shift();
var lng = process.argv.shift();
var distance = process.argv.shift();

var point = {
  "type": "Feature",
  "properties": {},
  "geometry": {
    "type": "Point",
    "coordinates": [lat, lng]
  }
};
var unit = 'kilometers';

var buffered = turf.buffer(point, distance, unit);

var features = buffered.features.concat(point);
var result = {
  "type": "FeatureCollection",
  "features": features
};

console.log(JSON.stringify(result));

e.g.

node buffer-point.js -122.43301391601562 37.7652868250379 2 | geojsonio