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The Easiest Way to Parse URLs with JavaScript

A very clever hack to parse a structured URL object is to create a <a> element and set its href to the URL you want to parse.

You can then query the <a> element for its components like schema, hostname, port, pathname, query, hash:

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var parser = document.createElement('a');
parser.href = 'http://heise.de/bar';
parser.hostname; // => 'heise.de'
pathname = parser.pathname; // => '/bar'

if (pathname[0] != '/')
  pathname = '/' + pathname // Fix IE11

One advantage vs. calling new URL(...) is that it works with incomplete URLs. So if all you have is /path it will fill in the hostname, protocol, etc. with data from the current page (as any <a> tag would do):

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var parser = document.createElement('a');
parser.href = 'foo'; // set the URL you want to parse (resolving relative paths in the context of the current URL)
parser.hostname; // => "makandracards.com"
parser.pathname; // => "/makandra/29377-the-easiest-way-to-parse-urls-with-javascript/foo"

if (pathname[0] != '/')
  pathname = '/' + pathname // Fix IE11

Caveat: IE11 will return the pathname without leading slash. Make to employ the fix as noted above.

If you use Unpoly you may also use up.util.parseUrl(), which implements the technique in this card with tests and all caveats fixed.

Related topic: Javascript: Read params from url.

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Owner of this card:

Henning Koch