function Request() {
    var src = document.location.search;
    if(src) src = src.substring(1);
    var ent = src.split('&');
    
    this.elements = [];
    for(var i=0; i<ent.length; i++) {
        var tmp = ent[i].split('=');
        this.elements[tmp[0]] = unescape(tmp[1]);
    }

    this.getParameter = function(name) {
        var val = this.elements[name];
        return val || null;
    }
}

request = new Request;
colour = request.getParameter('id');