[javascript] .substring error: "is not a function"

I don't understand why I get an error message using the substring method to declare a variable.

I want to use the first part of the URL in a comparison.

Site: http://www.elizabet.nl/wordpress

This is the part that's going wrong:

var currentLocation = document.location,
muzLoc = currentLocation.substring(0,45),
prodLoc = currentLocation.substring(0,48), 
techLoc = currentLocation.substring(0,47); 

The error: "currentLocation.substring is not a function"

But this part of the code is fine:

var URL = $(this).attr("href").substring(2) + ' #main';

All of the code:

jQuery(function($){

    var siteURL = "http://" + top.location.host.toString() + "/wordpress", // Declareren van URL van de website.
        URL = '', // Declareren van een URL, welke dan ook. 
        currentLocation = '',
        muzLoc = '',
        prodLoc = '',
        techLoc = '',               
        allLinks = $('a[href^=' + siteURL + ']' ), // Declareren van alle menu-links. Het teken ^ betekent 'begint met'.
        otherLinks = $('a[href^=' + siteURL + "/wp-content" + ']'), 
        siteLinks = $(allLinks).not(otherLinks),      
        mainDiv = $("#content"),
        hash = window.location.hash,
        muziekURL = "http://www.elizabet.nl/wordpress/#/muziek_pf/",
        productieURL = "http://www.elizabet.nl/wordpress/#/productie_pf/",
        techniekURL = "http://www.elizabet.nl/wordpress/#/techniek_pf/";    

    if (hash) {
        hash = "/wordpress" + hash.substring(1); // substring methode haalt karakters van je string af. In dit geval de #, vanwege de offset=1.
        URL = hash;
        $(mainDiv).load(URL);           
    }

function pageLoad() {

                var allLinks = $('a[href^=' + siteURL + ']' ),
                otherLinks = $('a[href^=' + siteURL + "/wp-content" + ']'), 
                siteLinks = $(allLinks).not(otherLinks); 

                siteLinks.each(function() {             

                    $(this).attr("href", "#" + this.pathname.substring(10));
                    })

                    .click(function() {
                    var URL = $(this).attr("href").substring(2) + ' #main';
                    $(mainDiv).load(URL, function(){ 

                    var currentLocation = document.location,
                        muzLoc = currentLocation.substring(0,45),
                        prodLoc = currentLocation.substring(0,48), 
                        techLoc = currentLocation.substring(0,47);                  

                if (muzLoc == muziekURL) {              
                $("body").animate({ backgroundColor: "#151C07"}, 500);
                $(".nieuws").animate({ borderBottomColor: "#99CC33"}, 500);  
                $("#stripe_trans").add("#header").animate({ backgroundColor: "#99CC33"}, 500);
                $("#tabtekst_3").stop().animate({ backgroundColor: "#B8860B" }, 500);
                $("#tab_3").add("a.gold").stop().animate({ color: "#B8860B" }, 500);
                $("#tabtekst_4").stop().animate({ backgroundColor: "#765AAD" }, 500);  
                $("#tab_4").add("a.purple").stop().animate({ color: "#765AAD" }, 500);                                    
                }

                else if (prodLoc == productieURL) {     
                $("body").animate({ backgroundColor: "#251B02"}, 500);  
                $(".nieuws").animate({ borderBottomColor: "#FFCC33"}, 500);  
                $("#stripe_trans").add("#header").animate({ backgroundColor: "#FFCC33"}, 500);                  
                $("#tabtekst_2").stop().animate({ backgroundColor: "#6B8E23" }, 500);  
                $("#tab_2").add("a.green").stop().animate({ color: "#6B8E23" }, 500);   
                $("#tabtekst_4").stop().animate({ backgroundColor: "#765AAD" }, 500);  
                $("#tab_4").add("a.purple").stop().animate({ color: "#765AAD" }, 500);
                } 

                else if (techLoc == techniekURL) {      
                $("body").animate({ backgroundColor: "#181223"}, 500);  
                $(".nieuws").animate({ borderBottomColor: "#B39BE4"}, 500);  
                $("#stripe_trans").add("#header").animate({ backgroundColor: "#B39BE4"}, 500);          
                $("#tabtekst_2").stop().animate({ backgroundColor: "#6B8E23" }, 500);  
                $("#tab_2").add("a.green").stop().animate({ color: "#6B8E23" }, 500);                       
                $("#tabtekst_3").stop().animate({ backgroundColor: "#B8860B" }, 500);
                $("#tab_3").add("a.gold").stop().animate({ color: "#B8860B" }, 500);
                } 

                else {
                $("body").animate({ backgroundColor: "#202020"}, 500);  
                $(".nieuws").animate({ borderBottomColor: "#FFF"}, 500);  
                $("#stripe_trans").add("#header").animate({ backgroundColor: "#FFF"}, 500);             
                $("#tabtekst_2").stop().animate({ backgroundColor: "#6B8E23" }, 500);  
                $("#tab_2").add("a.green").stop().animate({ color: "#6B8E23" }, 500);               
                $("#tabtekst_3").stop().animate({ backgroundColor: "#B8860B" }, 500);
                $("#tab_3").add("a.gold").stop().animate({ color: "#B8860B" }, 500);
                $("#tabtekst_4").stop().animate({ backgroundColor: "#765AAD" }, 500);  
                $("#tab_4").add("a.purple").stop().animate({ color: "#765AAD" }, 500);                                          
                }

                pageLoad();
            });             
        });
}

pageLoad();


}); // End document ready function.

you can also quote string

''+document.location+''.substring(2,3);

try this code below :

var currentLocation = document.location;
muzLoc = String(currentLocation).substring(0,45);
prodLoc = String(currentLocation).substring(0,48); 
techLoc = String(currentLocation).substring(0,47);

You can use substr

for example:

new Date().getFullYear().toString().substr(-2)

document.location is an object, not a string. It returns (by default) the full path, but it actually holds more info than that.

Shortcut for solution: document.location.toString().substring(2,3);

Or use document.location.href or window.location.href