路由的實現

(function() {

    var routes = [];
        
    //this will push the new route onto the 
    //list of routes.
    function addRoute(route, callback, scope){
        
        //create a consistent signature that 
        //we can rely on later
        var routeObj = {
            route: route,
            callback: callback,
            scope: scope
        };
        
        routes.push(routeObj);
    }
    
    //looks for matching routes, then calls the callback
    function handleRoute(path, noHistory) {
        
        var len = routes.length, scope;
        
        for (var i=0; i < len; i++) {
            if(path.match(routes[i].route)) {
                
                //if the caller provided a scope,
                //we use it, otherwise we will execute
                //the callback in the window scope
                if(routes[i].scope) {
                    scope = routes[i].scope;
                } else {
                    scope = window;
                }
                
                // if this is from a popstate,
                // we shouldn't push state again
                if(!noHistory) {
                    history.pushState({}, null, path);
                }
                
                //push the path onto the history stack
                routes[i].callback.apply(scope, [path]);
                return true;
            }
        }
        //no route found, move on
        return false;
    }
    
    window.addEventListener('popstate', function(e) {

        handleRoute(window.location.href, true);
    });
    
    window.router = {
        handleRoute:handleRoute,
        addRoute: addRoute
    };
    
})();