Get URL Parts In Javascript (Host, Path, File, Query, ETC…)

Welcome to a tutorial on how to get the full URL and parts in Javascript. Need to extract certain parts of the URL? Here are some of the common ones:

Yep, and there are a lot more on getting the specific URL parts in Javascript. Let us walk through more examples in this guide – Read on!

 

 

TABLE OF CONTENTS

 

 

PARTS OF THE URL

Before we proceed, here is a quick recap of the parts of the URL:

Yep, URLs are supposed to be “humanly legible”, but it is not really that straightforward.

 

 

PART 1) WINDOW LOCATION

When it comes to the URL, Javascript thankfully has a convenient window.location object (or just location for short). It pretty much contains all the various URL parts that we can use “out of the box”:

Variable	Description
location.href	This will give you the full URL. http://site.com:8080/path/file.html?p=123
location.protocol	Contains the protocol. http://site.com:8080/path/file.html?p=123
location.hostname	Contains the hostname. http://site.com:8080/path/file.html?p=123
location.host	Contains the hostname and the port. http://site.com:8080/path/file.html?p=123
location.origin	Contains the protocol, hostname, and port. http://site.com:8080/path/file.html?p=123
location.port	Contains the port number. http://site.com:8080/path/file.html?p=123
location.pathname	Contains the path and file name. http://site.com:8080/path/file.html?p=123
location.search	Contains the query string or parameter. http://site.com:8080/path/file.html?p=123
location.hash	Contains the hash anchor. http://site.com:8080/path/file.html#section-abc

 

 

PART 2) DERIVED URL PARTS

If the “URL part” that you require is not in location, the only way is to derive it yourself. Here are some of the common ones.

 

2A) FILE NAME ONLY

http://site.com:8080/path/file.html?p=123

// (A) FILE NAME ONLY
var fileonly = location.pathname;
// fileonly = fileonly.substring(fileonly.lastIndexOf("/")+1);
fileonly = fileonly.replace(/^.*[\\\/]/, "");
console.log(fileonly);

• location.pathname will give us the path and file name.
• We can use substring to “remove” the /path/ part.
• Or use replace regular expression to “extract” the file name only.

 

2B) PATH ONLY

http://site.com:8080/path/file.html?p=123

var pathonly = location.pathname;
pathonly = pathonly.substr(0, pathonly.lastIndexOf("/"));
console.log(pathonly);

This is similar to the “filename only”. But we strip out the file name and keep the path section instead.

 

 

2C) BASE URL

http://site.com:8080/path/file.html?p=123

// (C) BASE URL
var baseurl = `${location.protocol}//${location.host}${pathonly}/`;
console.log(baseurl);

This one should be straightforward. We “combine” the protocol, host, and derived path earlier to get the current base URL.

 

PART 3) WORKING WITH QUERY STRINGS

// (A) NEW SEARCH PARAMS OBJECT
// ASSUMING THAT WE START WITH ?KEY=VAL&FOO=BAR
var params = new URLSearchParams(location.search);

// (B) HAS KEY & GET VALUE
console.log(params.has("key")); // true
console.log(params.get("key")); // val

// (C) LOOP THROUGH ALL KEYS
for (let k of params.keys()) {
  console.log(k); // key, foo
}

// (D) APPEND, SET, DELETE
params.append("hello", "world"); // query string is now key=val&foo=bar&hello=world
params.set("hello", "kitty"); // query string is now key=val&foo=bar&hello=kitty
params.delete("key"); // query string is now foo=bar&hello=kitty
 
// (E) TO STRING
var str = params.toString();
console.log(str); // foo=bar&hello=kitty

Lastly, we can also parse the search parameters into a new URLSearchParams(location.search) object. This will “expand” the functionality, and allow us to easily work with the query string.

Function	Description
has(KEY)	Checks if the query string contains the given key.
get(KEY)	Get the value of the given key.
append(KEY, VALUE)	Append a new key/value pair to the query string
set(KEY, VALUE)	Sets the query string with the given key/value pair, will override the existing.
delete(KEY)	Delete the given key/value from the query string.
toString()	Converts the query into a flat string.

 

 

 

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EXAMPLE CODE DOWNLOAD

Click here for the source code on GitHub gist, just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

EXTRA – PARSE URL FROM STRING OR HTML ELEMENTS

<!-- (A) HTML ELEMENTS -->
<a id="demoA" href="https://code-boxx.com/path/file.html?key=val">Code Boxx</a>
<img id="demoB" src="baguette.png">
 
<script>
// (B) PARSE <A HREF>
let url = new URL(document.getElementById("demoA").href);
console.log(url.hostname); // code-boxx.com
console.log(url.pathname); // /path/file.html
 
// (C) PARSE <IMG SRC>
url = new URL(document.getElementById("demoB").src);
console.log(url.pathname); // /path/corgi.png
</script>

If you are not working with window.location, fear not. Simply parse the URL with new URL(URL STRING), and all the hostname pathname origin search etc... are still available.

 

REFERENCES & LINKS

• Window.location – MDN
• URLSearchParams – MDN
• Full URL and parts Yoga in PHP – Code Boxx

 

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