Update a DNS record using the Digital Ocean REST API. Configure using the constants at the top, run using "node update-dns". NB: borrows heavily from the PHP version from @bensquire called Digital-Ocean-Dynamic-DNS-Updater

update-dns.js

const ACCESS_TOKEN = '';
const DOMAIN = '';
const RECORD = '';

var http = require('http');
var https = require('https');
var when = require('when');
var color = require('bash-color');

var fetchExternalIp = function () {
	process.stdout.write('Fetching external ip...');
	return when.promise(function (resolve, reject) {
		var request = http.get("http://ipecho.net/plain", function (result) {
			var ip = "";
			result.on('data', function (chunk) {
				ip += chunk;
			});
			result.on('end', function () {
				resolve(ip);
			});
		});
	});
};

var verifyExternalIp = function (ip) {
	return when.promise(function (resolve, reject) {
		// IP address regex fetched from http://www.regular-expressions.info/examples.html
		if (/\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b/.test(ip)) {
			process.stdout.write(color.green(ip + '\n'));
			resolve(ip);
		} else {
			process.stdout.write(color.red('[FAIL]' + '\n'));
			reject('bad ip address');
		}
	});
};

var errorHandler = function (error) {
	process.stderr.write('Error: ' + error);
};

var fetchCurrentRecord = function (newIp) {
	process.stdout.write("Fetching current record...");
	return when.promise(function (resolve, reject) {
		// "https://api.digitalocean.com/v2/domains/" + DOMAIN + "/records"
		var request = https.get({
			hostname: "api.digitalocean.com",
			port: 443,
			path: "/v2/domains/" + DOMAIN + "/records",
			headers: {
				"Authorization": "Bearer " + ACCESS_TOKEN,
				"Accept": "application/json"
			}
		}, function (result) {
			var jsonResult = "";
			result.on('data', function (chunk) {
				jsonResult += chunk;
			});
			result.on('end', function () {
				var records = JSON.parse(jsonResult).domain_records;
				var findDomain = function (currentRecord) {
					return currentRecord.name === RECORD;
				};
				var validRecords = records.filter(findDomain);
				if (validRecords.length != 1) {
					process.stdout.write(color.red("[FAIL]") + "\n");
					reject('Too many or too few valid records: ', validRecords.length);
				} else {
					var currentIp = validRecords[0].data;
					var recordId = validRecords[0].id
					process.stdout.write(color.green(currentIp) + "\n");
					resolve({
						currentIp: currentIp, 
						newIp: newIp, 
						recordId: recordId
					});
				}
			});
		});
	});
};

var verifyCurrentRecord = function (args) {
	process.stdout.write("Verifying new ip is different from old ip...");
	return when.promise(function (resolve, reject) {
		if (args.currentIp === args.newIp) {
			process.stdout.write(color.yellow("MATCH") + "\n");
			resolve(false);
		} else {
			process.stdout.write(color.green("NO MATCH") + "\n");
			resolve(args);
		}
	});
};

var updateRecord = function (args) {
	return when.promise(function (resolve, reject) {
		var requestBody = {
			data: args.newIp
		};
		var requestBodyStr = JSON.stringify(requestBody);
		var req = https.request({
			hostname: "api.digitalocean.com",
			port: 443,
			method: 'PUT',
			path: "v2/domains/" + DOMAIN + "/records/" + args.recordId,
			headers: {
				"Authorization": "Bearer " + ACCESS_TOKEN,
				"Content-Type": "application/json",
				"Content-Length": requestBodyStr.length
			}
		});
		req.write(requestBodyStr);
		req.end();
	});
}

var maybeUpdateRecord = function (newIp, recordId) {
	return when.promise(function (resolve, reject) {
		if(newIp !== false) {
			process.stdout.write("Updating record...");
			updateRecord(newIp, recordId).then(resolve, reject);
		} else {
			process.stdout.write("Doing nothing (already up-to-date)\n");
		}
	});
}

var run = function () {
	process.stdout.write('Updating record: ' + RECORD + '.' + DOMAIN + ' at ' + (new Date()).toISOString() + '\n');
	fetchExternalIp()
		.then(verifyExternalIp)
		.then(fetchCurrentRecord)
		.then(verifyCurrentRecord)
		.then(maybeUpdateRecord)
		.catch(errorHandler)
		;
};


// finally, run the damn script
run();