URL API

Note: This feature is available in Web Workers.

The URL API is a component of the URL standard, which defines what constitutes a valid Uniform Resource Locator and the API that accesses and manipulates URLs. The URL standard also defines concepts such as domains, hosts, and IP addresses, and also attempts to describe in a standard way the legacy application/x-www-form-urlencoded MIME type used to submit web forms' contents as a set of key/value pairs.

Concepts and usage

The majority of the URL standard is taken up by the definition of a URL and how it is structured and parsed. Also covered are definitions of various terms related to addressing of computers on a network, and the algorithms for parsing IP addresses and DOM addresses are specified. More interesting to most developers is the API itself.

Accessing URL components

Creating an URL object for a given URL parses the URL and provides quick access to its constituent parts through its properties.

js
let addr = new URL("https://developer.mozilla.org/en-US/docs/Web/API/URL_API");
let host = addr.host;
let path = addr.pathname;

The snippet above creates a URL object for the article you're reading right now, then fetches the host and pathname properties. In this case, those strings are developer.mozilla.org and /en-US/docs/Web/API/URL_API, respectively.

Changing the URL

Most of the properties of URL are settable; you can write new values to them to alter the URL represented by the object. For example, to create a URL and set its username:

js
let myUsername = "some-guy";
let addr = new URL("https://example.com/login");
addr.username = myUsername;

Setting the value of username not only sets that property's value, but it updates the overall URL. After executing the code snippet above, the value returned by href is https://some-guy@example.com/login. This is true for any of the writable properties.

Queries

The search property on a URL contains the query string portion of the URL. For example, if the URL is https://example.com/login?user=some-guy&page=news, then the value of the search property is ?user=some-guy&page=news. You can also look up the values of individual parameters with the URLSearchParams object's get() method:

js
let addr = new URL("https://example.com/login?user=some-guy&page=news");
try {
  loginUser(addr.searchParams.get("user"));
  gotoPage(addr.searchParams.get("page"));
} catch (err) {
  showErrorMessage(err);
}

For example, in the above snippet, the username and target page are taken from the query and passed to appropriate functions that are used by the site's code to log in and route the user to their desired destination within the site.

Other functions within URLSearchParams let you change the value of keys, add and delete keys and their values, and even sort the list of parameters.

Interfaces

The URL API is a simple one, with only a couple of interfaces to its name:

URL

Can be used to parse, construct, normalize, and encode URLs.

URLSearchParams

Defines utility methods to work with the query string of a URL.

Examples

If you want to process the parameters included in a URL, you could do it manually, but it's much easier to create a URL object to do it for you. The fillTableWithParameters() function below takes as input a HTMLTableElement object representing a <table>. Rows are added to the table, one for each key found in the parameters, with the first column containing the key's name, and the second column having the value.

Note the call to URLSearchParams.sort() to sort the parameter list before generating the table.

js
function fillTableWithParameters(tbl) {
  const url = new URL(document.location.href);
  url.searchParams.sort();
  const keys = url.searchParams.keys();

  for (const key of keys) {
    const val = url.searchParams.get(key);
    const row = document.createElement("tr");
    const cell1 = document.createElement("td");
    cell1.innerText = key;
    row.appendChild(cell1);
    const cell2 = document.createElement("td");
    cell2.innerText = val;
    row.appendChild(cell2);
    tbl.appendChild(row);
  }
}

A working version of this example can be found on Glitch. Just add parameters to the URL when loading the page to see them in the table. For instance, try https://url-api.glitch.me?from=mdn&excitement=high&likelihood=inconceivable.

Specifications

Specification
URL
# api

Browser compatibility

api.URL

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
URL
URL() constructor
canParse() static method
createObjectURL() static method
hash
host
hostname
href
origin
parse() static method
password
pathname
port
protocol
revokeObjectURL() static method
search
searchParams
toJSON
toString
username

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
Partial support
Partial support
No support
No support
See implementation notes.
Requires a vendor prefix or different name for use.
Has more compatibility info.

api.URLSearchParams

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
URLSearchParams
[Symbol.iterator]
URLSearchParams() constructor
USVString for init object
record for init object
sequence for init object
append
delete
value parameter
entries
forEach
get
getAll
has
value parameter
keys
set
size
sort
toString
values

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
Partial support
Partial support
No support
No support
See implementation notes.
Has more compatibility info.

See also