使用JavaScript将相对路径转换为绝对路径

有一个功能，可以给我类似以下网址：

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

它总是一条相对路径。

假设我们知道页面的当前路径，例如http://site.com/stats/2012/，不确定如何将这些相对路径转换为真实路径？

我们应该得到这样的东西：

./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

没有jQuery，只有原始javascript。

应该这样做：

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("/");
}

最简单，有效和正确的方法是仅使用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
//=> "/programming/mypath"

在性能方面，此解决方案与使用字符串操作相当，并且是创建a标签的速度的两倍。

Javascript将为您完成。无需创建函数。

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"

但是，如果需要将其用作功能：

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

更新：如果需要完整的绝对路径，则为简单版本：

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

来自MDN的这是坚不可摧的！

/*\
|*|
|*|  :: 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);
}

用法示例：

/* 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

如果要对浏览器中的自定义网页（而不是运行脚本的页面）中的链接进行相对绝对转换，则可以使用@Bergi建议的功能的增强版本：

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('/');
}

null如果出现问题，它将返回。

用法：

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

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;
}

与其他解决方案不同，这也适用于IE6（请参阅从相对的解决方案获取绝对URL。（IE6问题））

提议并接受的解决方案不支持服务器相对URL，并且不适用于绝对URL。例如，如果我的亲戚是/ sites / folder1，它将无法正常工作。

这是另一个功能，它支持完整的服务器相对或相对URL以及上一级的../。它不是完美的，但是涵盖了很多选项。当您的基本URL不是当前页面URL时，请使用此选项，否则会有更好的选择。

    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;
}

希望这可以帮助。不能在JavaScript中使用此基本实用程序实在令人沮丧。

href解决方案仅在文档加载后才有效（至少在IE11中）。这为我工作：

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

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

我必须在接受的解决方案中添加一个修复程序，因为在angularjs导航中的＃号后面可以有斜线。

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("/");
}

我找到了一个非常简单的解决方案，同时仍可以通过使用历史记录API（IE 10或更高版本）来支持IE 10（IE不支持URL-API ）。此解决方案无需任何字符串操作即可工作。

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()不会触发浏览器导航，但仍会修改document.location并支持相对以及绝对路径。

该解决方案的一个缺点是，如果您已经在使用History-API并设置了带有标题的自定义状态，则当前状态的标题会丢失。

这会起作用。但仅当您打开带有文件名的页面时。当您打开这样的链接时，它将无法正常工作stackoverflow.com/page。它将与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;
}