Advanced URL Connection String parser + generator.

Usage no npm install needed!

<script type="module">
  import connectionString from '';



Advanced URL Connection String parser + generator, with fully optional syntax.

It takes a URL connection string (with every element being optional):


and converts it into an object that contains only what's specified:

    protocol: 'protocol',
    user: 'user',
    password: 'password',
    hosts: [
            {name: 'host1', port: 123, type: 'domain'},
            {name: '[abcd::]', port: 456, type: 'IPv6'}
            ], // = undefined when no hosts specified
    path: ['one', 'two'], // = undefined when no path specified
    params: {
        p1: 'val1',
        msg: 'hello world!'
    } // = undefined when no params specified

Plus it adds some Virtual Properties, to simplify access to the first host details.

And it can generate a valid connection string from an object (see connection-string-demo).

For documentation and examples, see WiKi Pages and API.


Unlike the default URL parser, this one supports the following:

  • Multiple hosts - for connecting to multiple servers
  • Fully optional syntax for every element in the connection string
  • It unifies Unix sockets support with the URL standard
  • Automatic defaults configuration for missing parameters
  • Re-construction of a connection string from object
  • Friendlier access to all of the URL's details

Short-syntax examples:

  • localhost => {hosts: [{name: 'localhost', type: 'domain'}]
  • localhost:12345 => {hosts: [{name: 'localhost', port: 12345, type: 'domain'}]
  • [12ab:34cd]:123 => {hosts: [{name: '[12ab:34cd]', port: 123, type: 'IPv6'}]
  • abc:///one?p1=val => {protocol: 'abc', path: ['one'], params: {p1: 'val'}}
  • :12345 => {hosts: [{port: 12345}]}
  • username@ => {user: 'username'}
  • :pass123@ => {password: 'pass123'}
  • /one/two => {path: ['one', 'two']}
  • ?p1=1&p2=a+b => {params: {p1: '1', p2: 'a b'}}

For more short-syntax examples see Optional Format.


$ npm i connection-string


  • TypeScript
import {ConnectionString} from 'connection-string';

const a = new ConnectionString('my-server:12345');
//=> {hosts: [{name: 'my-server', port: 12345, type: 'domain'}]}
  • Node.js
const {ConnectionString} = require('connection-string');

const obj = new ConnectionString('my-server:12345');
//=> {hosts: [{name: 'my-server', port: 12345, type: 'domain'}]}

See also WiKi Pages for more examples and documentation.

  • Browsers

TypeScript is the recommended way to include this library into a web application. Otherwise, you will have to Browserify distribution file dist/index.js, and then include the result. For more details, see Browsers page.


ConnectionString constructor accepts object defaults, as optional second parameter, to automatically call setDefaults in the end, to provide defaults for the values that are missing. See the method below.

The object returned by the parser will contain what's present in the connection string, combined with the defaults, if those were specified, plus methods as documented further.

setDefaults(defaults) => ConnectionString

The method takes an object with default values (unencoded), and safely combines it with what's missing in the current object.

Please note that while missing defaults for hosts and params are merged with the existing sets, for the path they are not, since their order is often important, so the defaults for path are only used when there are no path segments in the current object, though you can override the path manually, just like everything else in the object.

You can call this method either directly or when parsing/constructing the connection string, as the second parameter.

The method returns itself (the current object).

toString(options) => string

For the root ConnectionString object, the method generates a connection string from it.


const a = new ConnectionString('abc://localhost');
a.setDefaults({user: 'guest', password: 'pass123'});
a.toString(); //=> 'abc://guest:pass123@localhost'

You can also call toString() on both hosts property of the object, and individual host objects, if you want to generate a complete host name from the current properties.


const a = new ConnectionString('abc://my-host:123,[abcd::]:456');
a.hosts?.toString(); //=> 'my-host:123,[abcd::]:456'
a.hosts?.[0].toString(); //=> 'my-host:123'
a.hosts?.[1].toString(); //=> '[abcd::]:456'

The method takes one optional parameter - URL encoding options:

  • encodeDollar - Boolean (false), indicates whether $ should be encoded as %24. By default, $ is not URL-encoded, as it is not used very often, and even when it is used, it is usually either in the password or a parameter name, where encoding is typically not needed. But if you do need $ encoded everywhere, pass in {encodeDollar: true}.

  • plusForSpace - Boolean (false) - encodes spaces as + instead of %20.

  • passwordHash - Boolean (false)|String - replaces each password symbol with #, to generate a secure connection string. But when set to a non-empty string, its first symbol is used instead. Symbol # will prevent parsing such string again, on purpose. But if you want it parsed again, use a different symbol, for example - passwordHash: '*'

static parseHost(host) => {name, port, type} | null

When using an external list of default hosts (unencoded), you may need to parse them independently, using this method, so they can be correctly processed by method setDefaults.

const h = ConnectionString.parseHost('[abcd::]:111');
//=> {name: '[abcd::]', port: 111, type: 'IPv6'}

const a = new ConnectionString('test://localhost:222/dbname', {hosts: [h]});
//=> test://localhost:222,[abcd::]:111/dbname
  • Property type, when present, can be any of the following: domain | socket | IPv4 | IPv6.
  • If no valid host information is found, the method returns null.

For a good example, see connection-string-demo.

Virtual Properties

Type ConnectionString supports non-enumerable read-only properties host, hostname, port and type, for simpler use when you need only the first host details:

  • host = hosts?.[0].toString()
  • hostname = hosts?.[0].name
  • port = hosts?.[0].port
  • type = hosts?.[0].type


For some typical questions, consult the FAQ Page.