URL parsing utilities - Provides a shim for IE, where window.URL has a different meaning than in Chrome and Firefox

url.js

function _URL(url) {
    // Naive URL parser.  Assumes the input URL is valid.
    this.hash = "";
    this.search = "";
    this.pathname = "";
    this.port = "";
    this.hostname = "";
    this.host = "";
    this.password = "";
    this.username = "";
    this.protocol = "";
    this.origin = "";
    this.href = url;

    var hashIdx = url.indexOf("#");
    if (hashIdx > -1) {
        this.hash = url.slice(hashIdx);
        url = url.slice(0, hashIdx);
    }

    var searchIdx = url.indexOf("?");
    if (searchIdx > -1) {
        this.search = url.slice(searchIdx);
        url = url.slice(0, searchIdx);
    }

    var protoIdx = url.indexOf("://") + 1;
    this.protocol = url.slice(0, protoIdx);
    url = url.slice(protoIdx + 2);

    var slashIdx = url.indexOf("/");
    if (slashIdx > -1) {
        this.host = url.slice(0, slashIdx);
        this.pathname = url.slice(slashIdx);
    }
    else {
        this.host = url;
    }

    var userIdx = this.host.indexOf("@");
    if (userIdx > -1) {
        this.username = this.host.slice(0, userIdx);
        this.host = this.host.slice(userIdx + 1);
    }

    var pwdIdx = this.username.indexOf(":");
    if (pwdIdx > -1) {
        this.password = this.username.slice(pwdIdx + 1);
        this.username = this.username.slice(0, pwdIdx);
    }

    var portIdx = this.host.indexOf(":");
    if (portIdx > -1) {
        this.hostname = this.host.slice(0, portIdx);
        this.port = this.host.slice(portIdx + 1);
    }
    else {
        this.hostname = this.host;
    }

    this.origin = this.protocol + "//" + this.host;
}

function parseUrlArgs(argString) {
    // Decode key value pairs in url.search or url.hash into an Object
    // Values are all strings.
    // Values for duplicate keys are wrapped in arrays.
    // Values for keys with '=' but no value (eg, &key=&) are empty strings.
    // Values for keys without '=' (eg, &key&) are null.
    // This function expects a URI Encoded string including the leading ? or #. 
    // So standard strings can be passed, eg, location.search, URI.hash, etc.
    var args = {};
    argString.slice(1).split("&").forEach(function (arg) {
        if (!arg) return;
        var parts = arg.split("=");
        var key = decodeURLComponent(parts[0]);
        var val = parts.length > 1 ? decodeURLComponent(parts[1]) : null;

        if (key in args) {
            if (!(args[key] instanceof array)) {
                args[key] = [args[key]];
            }
            args[key].push(val);
        }
        else {
            args[key] = val;
        }
    });
    return args;
}
function decodeURLComponent(s) {
    // interpret + in URLs as space
    return decodeURIComponent(s.replace(/\+/g, " "));
}
function encodeURLComponent(s) {
    // encode space in URLs with +
    return encodeURIComponent(s).replace(/%20/g, "+");
}

// Using typeof because window.URL is defined in IE10+, but as an object, not a function
var URL = typeof window.URL === "function" ? window.URL : _URL;