Simplify GeoJSON using d3-plugins/simplify (thanks @jasondavies for preserving topology!)

convert.js

// TODO: options parser with overrides for projection, area etc.
if (process.argv.length != 4) {
  console.error("usage: node convert.js <input.json> <output.json>");
  process.exit(1);
}

require('d3')
require('./node_modules/d3-plugins/simplify/simplify.js')

var fs = require('fs');

var simplify = d3.simplify()
	.area(0)
	.topology(true)
	.projection(function(c){ return c; });

console.log('reading input...');
var raw = fs.readFileSync(process.argv[2],'utf8')

console.log('parsing input...');
var data = JSON.parse(raw);

console.log('simplifying...')
var geography = simplify.project(data);
var simple = simplify(geography);

console.log('stringifying output...')
var out = JSON.stringify(simple);

console.log('writing output...')
fs.writeFileSync(process.argv[3], out);

console.log('done!');