The URL() constructor returns a newly created URL object representing the URL defined by the parameters.

If the given base URL or the resulting URL are not valid URLs, the JavaScript TypeError exception is thrown.

Note: This feature is available in Web Workers.


const url = new URL(url [, base])


A USVString representing an absolute or relative URL. If url is a relative URL, base is required, and will be used as the base URL. If url is an absolute URL, a given base will be ignored.
base Optional
A USVString representing the base URL to use in case url is a relative URL. If not specified, it defaults to ''.

Note: You can still use an existing URL object for the base, which stringifies itself to the object's href property.


Exception Explanation
TypeError url (in the case of absolute URLs) or base + url (in the case of relative URLs) is not a valid URL.


// Base urls
let m = 'https://developer.mozilla.org';
let a = new URL("/", m);                                // => 'https://developer.mozilla.org/'
let b = new URL(m);                                     // => 'https://developer.mozilla.org/'

        new URL('en-US/docs', b);                      // => 'https://developer.mozilla.org/en-US/docs'
let d = new URL('/en-US/docs', b);                     // => 'https://developer.mozilla.org/en-US/docs'
        new URL('/en-US/docs', d);                     // => 'https://developer.mozilla.org/en-US/docs'
        new URL('/en-US/docs', a);                     // => 'https://developer.mozilla.org/en-US/docs'
        new URL('/en-US/docs', "https://developer.mozilla.org/fr-FR/toto");
                                                       // => 'https://developer.mozilla.org/en-US/docs'
        new URL('/en-US/docs', '');                    // Raises a TypeError exception as '' is not a valid URL
        new URL('/en-US/docs');                        // Raises a TypeError exception as '/en-US/docs' is not a valid URL
        new URL('http://www.example.com', );           // => 'http://www.example.com/'
        new URL('http://www.example.com', b);          // => 'http://www.example.com/'

        new URL("//foo.com", "https://example.com")    // => 'https://foo.com' (see relative URLs)


Specification Status Comment
The definition of 'URL.URL()' in that specification.
Living Standard Initial definition.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
URL() constructorChrome Full support 19Edge Full support 12Firefox Full support 26IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support ≤37Chrome Android Full support 25Firefox Android Full support 26Opera Android Full support 14Safari iOS Full support 6Samsung Internet Android Full support 1.5


Full support  
Full support
No support  
No support

See also

  • The interface it belongs to: URL.