function normalizeUrl(pathComponents){ 
return pathComponents.reduce(function (accumulator, item){ 
switch (item){ 
case "..": accumulator.pop(); 
break ; 
case ".": break ; 
default : { 
accumulator.push(item); 
} 
} 
return accumulator; 
} 
, ([] )).join("/"); 
} 
module.exports = function (urlString){ 
urlString = urlString.trim(); 
if (/^data:/i.test(urlString)) { 
return urlString; 
} 
var protocol = urlString.indexOf("//") !== -1? urlString.split("//")[0] + "//": ""; 
var components = _AN_Call_replace("replace", urlString, new RegExp(protocol, "i"), "").split("/"); 
var host = _AN_Call_replace("replace", components[0].toLowerCase(), /\.$/, ""); 
components[0] = ""; 
var path = normalizeUrl(components); 
return protocol + host + path; 
} 
;