Node.js v18.20.0 documentation

URL strings and URL objects#

A URL string is a structured string containing multiple meaningful components. When parsed, a URL object is returned containing properties for each of these components.

The node:url module provides two APIs for working with URLs: a legacy API that is Node.js specific, and a newer API that implements the same WHATWG URL Standard used by web browsers.

A comparison between the WHATWG and legacy APIs is provided below. Above the URL 'https://user:pass@sub.example.com:8080/p/a/t/h?query=string#hash', properties of an object returned by the legacy url.parse() are shown. Below it are properties of a WHATWG URL object.

WHATWG URL's origin property includes protocol and host, but not username or password.

┌────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                              href                                              │
├──────────┬──┬─────────────────────┬────────────────────────┬───────────────────────────┬───────┤
│ protocol │  │        auth         │          host          │           path            │ hash  │
│          │  │                     ├─────────────────┬──────┼──────────┬────────────────┤       │
│          │  │                     │    hostname     │ port │ pathname │     search     │       │
│          │  │                     │                 │      │          ├─┬──────────────┤       │
│          │  │                     │                 │      │          │ │    query     │       │
"  https:   //    user   :   pass   @ sub.example.com : 8080   /p/a/t/h  ?  query=string   #hash "
│          │  │          │          │    hostname     │ port │          │                │       │
│          │  │          │          ├─────────────────┴──────┤          │                │       │
│ protocol │  │ username │ password │          host          │          │                │       │
├──────────┴──┼──────────┴──────────┼────────────────────────┤          │                │       │
│   origin    │                     │         origin         │ pathname │     search     │ hash  │
├─────────────┴─────────────────────┴────────────────────────┴──────────┴────────────────┴───────┤
│                                              href                                              │
└────────────────────────────────────────────────────────────────────────────────────────────────┘
(All spaces in the "" line should be ignored. They are purely for formatting.) copy

Parsing the URL string using the WHATWG API:

const myURL =
  new URL('https://user:pass@sub.example.com:8080/p/a/t/h?query=string#hash'); copy

Parsing the URL string using the legacy API:

import url from 'node:url';
const myURL =
  url.parse('https://user:pass@sub.example.com:8080/p/a/t/h?query=string#hash');const url = require('node:url');
const myURL =
  url.parse('https://user:pass@sub.example.com:8080/p/a/t/h?query=string#hash');copy

Constructing a URL from component parts and getting the constructed string#

It is possible to construct a WHATWG URL from component parts using either the property setters or a template literal string:

const myURL = new URL('https://example.org');
myURL.pathname = '/a/b/c';
myURL.search = '?d=e';
myURL.hash = '#fgh'; copy

const pathname = '/a/b/c';
const search = '?d=e';
const hash = '#fgh';
const myURL = new URL(`https://example.org${pathname}${search}${hash}`); copy

To get the constructed URL string, use the href property accessor:

console.log(myURL.href); copy

The WHATWG URL API#

Class: URL#

Browser-compatible URL class, implemented by following the WHATWG URL Standard. Examples of parsed URLs may be found in the Standard itself. The URL class is also available on the global object.

In accordance with browser conventions, all properties of URL objects are implemented as getters and setters on the class prototype, rather than as data properties on the object itself. Thus, unlike legacy urlObjects, using the delete keyword on any properties of URL objects (e.g. delete myURL.protocol, delete myURL.pathname, etc) has no effect but will still return true.

new URL(input[, base])#

• input <string> The absolute or relative input URL to parse. If input is relative, then base is required. If input is absolute, the base is ignored. If input is not a string, it is converted to a string first.
• base <string> The base URL to resolve against if the input is not absolute. If base is not a string, it is converted to a string first.

Creates a new URL object by parsing the input relative to the base. If base is passed as a string, it will be parsed equivalent to new URL(base).

const myURL = new URL('/foo', 'https://example.org/');
// https://example.org/foo copy

The URL constructor is accessible as a property on the global object. It can also be imported from the built-in url module:

import { URL } from 'node:url';
console.log(URL === globalThis.URL); // Prints 'true'.console.log(URL === require('node:url').URL); // Prints 'true'.copy

A TypeError will be thrown if the input or base are not valid URLs. Note that an effort will be made to coerce the given values into strings. For instance:

const myURL = new URL({ toString: () => 'https://example.org/' });
// https://example.org/ copy

Unicode characters appearing within the host name of input will be automatically converted to ASCII using the Punycode algorithm.

const myURL = new URL('https://測試');
// https://xn--g6w251d/ copy

In cases where it is not known in advance if input is an absolute URL and a base is provided, it is advised to validate that the origin of the URL object is what is expected.

let myURL = new URL('http://Example.com/', 'https://example.org/');
// http://example.com/

myURL = new URL('https://Example.com/', 'https://example.org/');
// https://example.com/

myURL = new URL('foo://Example.com/', 'https://example.org/');
// foo://Example.com/

myURL = new URL('http:Example.com/', 'https://example.org/');
// http://example.com/

myURL = new URL('https:Example.com/', 'https://example.org/');
// https://example.org/Example.com/

myURL = new URL('foo:Example.com/', 'https://example.org/');
// foo:Example.com/ copy

url.hash#

• <string>

Gets and sets the fragment portion of the URL.

const myURL = new URL('https://example.org/foo#bar');
console.log(myURL.hash);
// Prints #bar

myURL.hash = 'baz';
console.log(myURL.href);
// Prints https://example.org/foo#baz copy

Invalid URL characters included in the value assigned to the hash property are percent-encoded. The selection of which characters to percent-encode may vary somewhat from what the url.parse() and url.format() methods would produce.

url.host#

• <string>

Gets and sets the host portion of the URL.

const myURL = new URL('https://example.org:81/foo');
console.log(myURL.host);
// Prints example.org:81

myURL.host = 'example.com:82';
console.log(myURL.href);
// Prints https://example.com:82/foo copy

Invalid host values assigned to the host property are ignored.

url.hostname#

• <string>

Gets and sets the host name portion of the URL. The key difference between url.host and url.hostname is that url.hostname does not include the port.

const myURL = new URL('https://example.org:81/foo');
console.log(myURL.hostname);
// Prints example.org

// Setting the hostname does not change the port
myURL.hostname = 'example.com';
console.log(myURL.href);
// Prints https://example.com:81/foo

// Use myURL.host to change the hostname and port
myURL.host = 'example.org:82';
console.log(myURL.href);
// Prints https://example.org:82/foo copy

Invalid host name values assigned to the hostname property are ignored.

url.href#

• <string>

Gets and sets the serialized URL.

const myURL = new URL('https://example.org/foo');
console.log(myURL.href);
// Prints https://example.org/foo

myURL.href = 'https://example.com/bar';
console.log(myURL.href);
// Prints https://example.com/bar copy

Getting the value of the href property is equivalent to calling url.toString().

Setting the value of this property to a new value is equivalent to creating a new URL object using new URL(value). Each of the URL object's properties will be modified.

If the value assigned to the href property is not a valid URL, a TypeError will be thrown.

url.origin#

• <string>

Gets the read-only serialization of the URL's origin.

const myURL = new URL('https://example.org/foo/bar?baz');
console.log(myURL.origin);
// Prints https://example.org copy

const idnURL = new URL('https://測試');
console.log(idnURL.origin);
// Prints https://xn--g6w251d

console.log(idnURL.hostname);
// Prints xn--g6w251d copy

url.password#

• <string>

Gets and sets the password portion of the URL.

const myURL = new URL('https://abc:xyz@example.com');
console.log(myURL.password);
// Prints xyz

myURL.password = '123';
console.log(myURL.href);
// Prints https://abc:123@example.com/ copy

Invalid URL characters included in the value assigned to the password property are percent-encoded. The selection of which characters to percent-encode may vary somewhat from what the url.parse() and url.format() methods would produce.

url.pathname#

• <string>

Gets and sets the path portion of the URL.

const myURL = new URL('https://example.org/abc/xyz?123');
console.log(myURL.pathname);
// Prints /abc/xyz

myURL.pathname = '/abcdef';
console.log(myURL.href);
// Prints https://example.org/abcdef?123 copy

Invalid URL characters included in the value assigned to the pathname property are percent-encoded. The selection of which characters to percent-encode may vary somewhat from what the url.parse() and url.format() methods would produce.

url.port#

• <string>

Gets and sets the port portion of the URL.

The port value may be a number or a string containing a number in the range 0 to 65535 (inclusive). Setting the value to the default port of the URL objects given protocol will result in the port value becoming the empty string ('').

The port value can be an empty string in which case the port depends on the protocol/scheme:

Upon assigning a value to the port, the value will first be converted to a string using .toString().

If that string is invalid but it begins with a number, the leading number is assigned to port. If the number lies outside the range denoted above, it is ignored.

const myURL = new URL('https://example.org:8888');
console.log(myURL.port);
// Prints 8888

// Default ports are automatically transformed to the empty string
// (HTTPS protocol's default port is 443)
myURL.port = '443';
console.log(myURL.port);
// Prints the empty string
console.log(myURL.href);
// Prints https://example.org/

myURL.port = 1234;
console.log(myURL.port);
// Prints 1234
console.log(myURL.href);
// Prints https://example.org:1234/

// Completely invalid port strings are ignored
myURL.port = 'abcd';
console.log(myURL.port);
// Prints 1234

// Leading numbers are treated as a port number
myURL.port = '5678abcd';
console.log(myURL.port);
// Prints 5678

// Non-integers are truncated
myURL.port = 1234.5678;
console.log(myURL.port);
// Prints 1234

// Out-of-range numbers which are not represented in scientific notation
// will be ignored.
myURL.port = 1e10; // 10000000000, will be range-checked as described below
console.log(myURL.port);
// Prints 1234 copy

Numbers which contain a decimal point, such as floating-point numbers or numbers in scientific notation, are not an exception to this rule. Leading numbers up to the decimal point will be set as the URL's port, assuming they are valid:

myURL.port = 4.567e21;
console.log(myURL.port);
// Prints 4 (because it is the leading number in the string '4.567e21') copy

url.protocol#

• <string>

Gets and sets the protocol portion of the URL.

const myURL = new URL('https://example.org');
console.log(myURL.protocol);
// Prints https:

myURL.protocol = 'ftp';
console.log(myURL.href);
// Prints ftp://example.org/ copy

Invalid URL protocol values assigned to the protocol property are ignored.

Special schemes#

The WHATWG URL Standard considers a handful of URL protocol schemes to be special in terms of how they are parsed and serialized. When a URL is parsed using one of these special protocols, the url.protocol property may be changed to another special protocol but cannot be changed to a non-special protocol, and vice versa.

For instance, changing from http to https works:

const u = new URL('http://example.org');
u.protocol = 'https';
console.log(u.href);
// https://example.org/ copy

However, changing from http to a hypothetical fish protocol does not because the new protocol is not special.

const u = new URL('http://example.org');
u.protocol = 'fish';
console.log(u.href);
// http://example.org/ copy

Likewise, changing from a non-special protocol to a special protocol is also not permitted:

const u = new URL('fish://example.org');
u.protocol = 'http';
console.log(u.href);
// fish://example.org copy

According to the WHATWG URL Standard, special protocol schemes are ftp, file, http, https, ws, and wss.

url.search#

• <string>

Gets and sets the serialized query portion of the URL.

const myURL = new URL('https://example.org/abc?123');
console.log(myURL.search);
// Prints ?123

myURL.search = 'abc=xyz';
console.log(myURL.href);
// Prints https://example.org/abc?abc=xyz copy

Any invalid URL characters appearing in the value assigned the search property will be percent-encoded. The selection of which characters to percent-encode may vary somewhat from what the url.parse() and url.format() methods would produce.

url.searchParams#

• <URLSearchParams>

Gets the URLSearchParams object representing the query parameters of the URL. This property is read-only but the URLSearchParams object it provides can be used to mutate the URL instance; to replace the entirety of query parameters of the URL, use the url.search setter. See URLSearchParams documentation for details.

Use care when using .searchParams to modify the URL because, per the WHATWG specification, the URLSearchParams object uses different rules to determine which characters to percent-encode. For instance, the URL object will not percent encode the ASCII tilde (~) character, while URLSearchParams will always encode it:

const myURL = new