//javascript.js**************
function Section() {
    this.currentKey;
    this.offsets = [];
    this.sectionID;
    this.prefixPath;
    this.topOffset;
}

//constructor
Section.prototype.construct = function (topOffset) {

    this.sectionID = ['heim', 'tilbud', 'galleri', 'feedback'];
    this.prefixPath = 'body>section#content>section#';
    this.topOffset = topOffset;

    //sets the offsets values
    for (var u = 0; u < this.sectionID.length; u++) {
        this.offsets[u] = $(this.prefixPath+this.sectionID[u]).offset().top;
    }
    return false;
}

//change attribute
Section.prototype.changeIDString = function () {
    //gets the currentKey
    for (var i = 0; i < this.offsets.length; i++) {
        if (i + 1 != this.offsets.length) {
            if (this.topOffset >= this.offsets[i] && this.topOffset < this.offsets[i + 1]) {
                this.currentKey = i;
                break;
            }
        } else if (this.topOffset >= this.offsets[i]) {
            this.currentKey = i;
            break;
        }
    }
    return false;
}

//get current
Section.prototype.getIDString = function () {
    return this.sectionID[this.currentKey];
}

//set classes
Section.prototype.setAttributes = function () {
    $('#current').removeAttr('id');
    $('[data-gotoSection="#' + this.getIDString() + '"]').attr('id', 'current');
}


var Section = new Section();



//footer.php*****************
[...]
    //find the section
    Section.construct(topOffset);
    Section.changeIDString();
    Section.setAttributes();
[...]