Convert relative path to absolute using JavaScript

Javascript Problem Overview

There's a function, which gives me urls like:

./some.css
./extra/some.css
../../lib/slider/slider.css

It's always a relative path.

Let's think we know current path of the page, like http://site.com/stats/2012/, not sure how do I convert these relative paths to real ones?

We should get something like:

./some.css => http://site.com/stats/2012/some.css
./extra/some.css => http://site.com/stats/2012/extra/some.css
../../lib/slider/slider.css => http://site.com/lib/slider/slider.css

No jQuery, only vanilla javascript.

Javascript Solutions

Solution 1 - Javascript

The most simple, efficient and correct way to do so it to just use URL api.

new URL("http://www.stackoverflow.com?q=hello").href;
//=> http://www.stackoverflow.com/?q=hello"

new URL("mypath","http://www.stackoverflow.com").href;
//=> "http://www.stackoverflow.com/mypath"

new URL("../mypath","http://www.stackoverflow.com/search").href
//=> "http://www.stackoverflow.com/mypath"

new URL("../mypath", document.baseURI).href
//=> "https://stackoverflow.com/questions/mypath"

Performance wise, this solution is on par with using string manipulation and twice as fast as creating a tag.

Solution 2 - Javascript

Javascript will do it for you. There's no need to create a function.

var link = document.createElement("a");
link.href = "../../lib/slider/slider.css";
alert(link.protocol+"//"+link.host+link.pathname+link.search+link.hash);

// Output will be "http://www.yoursite.com/lib/slider/slider.css"

But if you need it as a function:

var absolutePath = function(href) {
    var link = document.createElement("a");
    link.href = href;
    return (link.protocol+"//"+link.host+link.pathname+link.search+link.hash);
}

Update: Simpler version if you need the full absolute path:

var absolutePath = function(href) {
    var link = document.createElement("a");
    link.href = href;
    return link.href;
}

Solution 3 - Javascript

This should do it:

function absolute(base, relative) {
    var stack = base.split("/"),
        parts = relative.split("/");
    stack.pop(); // remove current file name (or empty string)
                 // (omit if "base" is the current folder without trailing slash)
    for (var i=0; i<parts.length; i++) {
        if (parts[i] == ".")
            continue;
        if (parts[i] == "..")
            stack.pop();
        else
            stack.push(parts[i]);
    }
    return stack.join("/");
}

Solution 4 - Javascript

This from MDN is unbreakable!

/*\
|*|
|*|  :: translate relative paths to absolute paths ::
|*|
|*|  https://developer.mozilla.org/en-US/docs/Web/API/document.cookie
|*|
|*|  The following code is released under the GNU Public License, version 3 or later.
|*|  http://www.gnu.org/licenses/gpl-3.0-standalone.html
|*|
\*/

function relPathToAbs (sRelPath) {
  var nUpLn, sDir = "", sPath = location.pathname.replace(/[^\/]*$/, sRelPath.replace(/(\/|^)(?:\.?\/+)+/g, "$1"));
  for (var nEnd, nStart = 0; nEnd = sPath.indexOf("/../", nStart), nEnd > -1; nStart = nEnd + nUpLn) {
    nUpLn = /^\/(?:\.\.\/)*/.exec(sPath.slice(nEnd))[0].length;
    sDir = (sDir + sPath.substring(nStart, nEnd)).replace(new RegExp("(?:\\\/+[^\\\/]*){0," + ((nUpLn - 1) / 3) + "}$"), "/");
  }
  return sDir + sPath.substr(nStart);
}

Sample usage:

/* Let us be in /en-US/docs/Web/API/document.cookie */

alert(location.pathname);
// displays: /en-US/docs/Web/API/document.cookie

alert(relPathToAbs("./"));
// displays: /en-US/docs/Web/API/

alert(relPathToAbs("../Guide/API/DOM/Storage"));
// displays: /en-US/docs/Web/Guide/API/DOM/Storage

alert(relPathToAbs("../../Firefox"));
// displays: /en-US/docs/Firefox

alert(relPathToAbs("../Guide/././API/../../../Firefox"));
// displays: /en-US/docs/Firefox

Solution 5 - Javascript

If you want to make a relative-to-absolute conversion for a link from a custom webpage in your browser (not for the page that runs your script), you can use a more enhanced version of the function suggested by @Bergi:

var resolveURL=function resolve(url, base){
	if('string'!==typeof url || !url){
		return null; // wrong or empty url
	}
	else if(url.match(/^[a-z]+\:\/\//i)){ 
		return url; // url is absolute already 
	}
	else if(url.match(/^\/\//)){ 
		return 'http:'+url; // url is absolute already 
	}
	else if(url.match(/^[a-z]+\:/i)){ 
		return url; // data URI, mailto:, tel:, etc.
	}
	else if('string'!==typeof base){
		var a=document.createElement('a'); 
		a.href=url; // try to resolve url without base  
		if(!a.pathname){ 
			return null; // url not valid 
		}
		return 'http://'+url;
	}
	else{ 
		base=resolve(base); // check base
		if(base===null){
			return null; // wrong base
		}
	}
	var a=document.createElement('a'); 
	a.href=base;
	
	if(url[0]==='/'){ 
		base=[]; // rooted path
	}
	else{ 
		base=a.pathname.split('/'); // relative path
		base.pop(); 
	}
	url=url.split('/');
	for(var i=0; i<url.length; ++i){
		if(url[i]==='.'){ // current directory
			continue;
		}
		if(url[i]==='..'){ // parent directory
			if('undefined'===typeof base.pop() || base.length===0){ 
				return null; // wrong url accessing non-existing parent directories
			}
		}
		else{ // child directory
			base.push(url[i]); 
		}
	}
	return a.protocol+'//'+a.hostname+base.join('/');
}

It'll return null if something is wrong.

Usage:

resolveURL('./some.css', 'http://example.com/stats/2012/'); 
// returns http://example.com/stats/2012/some.css

resolveURL('extra/some.css', 'http://example.com/stats/2012/');
// returns http://example.com/stats/2012/extra/some.css

resolveURL('../../lib/slider/slider.css', 'http://example.com/stats/2012/');
// returns http://example.com/lib/slider/slider.css

resolveURL('/rootFolder/some.css', 'https://example.com/stats/2012/');
// returns https://example.com/rootFolder/some.css

resolveURL('localhost');
// returns http://localhost

resolveURL('../non_existing_file', 'example.com')
// returns null

Solution 6 - Javascript

I know this is a very old question, but you could do it with: (new URL(relativePath, location)).href.

Solution 7 - Javascript

The href solution only works once the document is loaded (at least in IE11). This worked for me:

link = link || document.createElement("a");
link.href =  document.baseURI + "/../" + href;
return link.href;

See https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base

Solution 8 - Javascript

function canonicalize(url) {
    var div = document.createElement('div');
    div.innerHTML = "<a></a>";
    div.firstChild.href = url; // Ensures that the href is properly escaped
    div.innerHTML = div.innerHTML; // Run the current innerHTML back through the parser
    return div.firstChild.href;
}

This works on IE6 too, unlike some other solutions (see https://stackoverflow.com/questions/470832/getting-an-absolute-url-from-a-relative-one-ie6-issue)

Solution 9 - Javascript

The proposed and accepted solution does not support server relative URLs and does not work on absolute URLs. If my relative is /sites/folder1 it won't work for example.

Here is another function that supports full, server relative or relative URLs as well as ../ for one level up. It is not perfect but covers a lot of options. Use this when your base URL is not the current page URL, otherwise there are better alternatives.

    function relativeToAbsolute(base, relative) {
    //make sure base ends with /
    if (base[base.length - 1] != '/')
        base += '/';

    //base: https://server/relative/subfolder/
    //url: https://server
    let url = base.substr(0, base.indexOf('/', base.indexOf('//') + 2));
    //baseServerRelative: /relative/subfolder/
    let baseServerRelative = base.substr(base.indexOf('/', base.indexOf('//') + 2));
    if (relative.indexOf('/') === 0)//relative is server relative
        url += relative;
    else if (relative.indexOf("://") > 0)//relative is a full url, ignore base.
        url = relative;
    else {
        while (relative.indexOf('../') === 0) {
            //remove ../ from relative
            relative = relative.substring(3);
            //remove one part from baseServerRelative. /relative/subfolder/ -> /relative/
            if (baseServerRelative !== '/') {
                let lastPartIndex = baseServerRelative.lastIndexOf('/', baseServerRelative.length - 2);
                baseServerRelative = baseServerRelative.substring(0, lastPartIndex + 1);
            }
        }
        url += baseServerRelative + relative;//relative is a relative to base.
    }

    return url;
}

Hope this helps. It was really frustrating not to have this basic utility available in JavaScript.

Solution 10 - Javascript

I had to add a fix to the accepted solution because we can have slashes after # in our angularjs navigation.

function getAbsoluteUrl(base, relative) {
  // remove everything after #
  var hashPosition = base.indexOf('#');
  if (hashPosition > 0){
    base = base.slice(0, hashPosition);
  }

  // the rest of the function is taken from http://stackoverflow.com/a/14780463
  // http://stackoverflow.com/a/25833886 - this doesn't work in cordova
  // http://stackoverflow.com/a/14781678 - this doesn't work in cordova
  var stack = base.split("/"),
      parts = relative.split("/");
  stack.pop(); // remove current file name (or empty string)
               // (omit if "base" is the current folder without trailing slash)
  for (var i=0; i<parts.length; i++) {
    if (parts[i] == ".")
      continue;
    if (parts[i] == "..")
      stack.pop();
    else
      stack.push(parts[i]);
  }
  return stack.join("/");
}

Solution 11 - Javascript

I found a very simple solution to do this while still supporting IE 10 (IE doesn't support the URL-API) by using the History API (IE 10 or higher). This solution works without any string manipulation.

function resolveUrl(relativePath) {
    var originalUrl = document.location.href;
    history.replaceState(history.state, '', relativePath);
    var resolvedUrl = document.location.href;
    history.replaceState(history.state, '', originalUrl);
    return resolvedUrl;
}

history.replaceState() won't trigger browser navigation, but will still modify document.location and supports relative aswell as absolute paths.

The one drawback of this solution is that if you are already using the History-API and have set a custom state with a title, the current state's title is lost.

Solution 12 - Javascript

This will work. but only when you open a page with it's file name. it will not work well when you open a link like this stackoverflow.com/page. it will work with stackoverflow.com/page/index.php

function reltoabs(link){
	let absLink = location.href.split("/");
	let relLink = link;
	let slashesNum = link.match(/[.]{2}\//g) ? link.match(/[.]{2}\//g).length : 0;
	for(let i = 0; i < slashesNum + 1; i++){
		relLink = relLink.replace("../", "");
		absLink.pop();
	}
	absLink = absLink.join("/");
	absLink += "/" + relLink;
	return absLink;
}

Content Type	Original Author	Original Content on Stackoverflow
Question	Jasper	View Question on Stackoverflow
Solution 1 - Javascript	Elad	View Answer on Stackoverflow
Solution 2 - Javascript	allenhwkim	View Answer on Stackoverflow
Solution 3 - Javascript	Bergi	View Answer on Stackoverflow
Solution 4 - Javascript	madmurphy	View Answer on Stackoverflow
Solution 5 - Javascript	optimizitor	View Answer on Stackoverflow
Solution 6 - Javascript	illogicalapple	View Answer on Stackoverflow
Solution 7 - Javascript	Corey Alix	View Answer on Stackoverflow
Solution 8 - Javascript	Sebastien Lorber	View Answer on Stackoverflow
Solution 9 - Javascript	Shai Petel	View Answer on Stackoverflow
Solution 10 - Javascript	Stanislav	View Answer on Stackoverflow
Solution 11 - Javascript	whY	View Answer on Stackoverflow
Solution 12 - Javascript	Mohamed hesham	View Answer on Stackoverflow