Highlighting current navigation state in Backbone.

问题:

I want to highlight the current navigation state. Like if the hashchange is #home, I want to style the 'Home' menu link differently and similarly other links.

Backbone.js fires individual events like route:home,... route:some-other when the #home and other links are clicked. I could not see any common event that will be fired for every hashchange. With this I m required to write the state highlight logic by binding to all the route events, which I think is not good solution.

So, I've overridden Backbone.Router.route in my router sub class/object, like

// override backbone' Router.route method to publish 
// common 'route_change' event for any hash change
route : function(route, name, callback) {
    Backbone.history || (Backbone.history = new Backbone.History);
    if (!_.isRegExp(route)) route = this._routeToRegExp(route);
    Backbone.history.route(route, _.bind(function(fragment) {
        var args = this._extractParameters(route, fragment);
        callback.apply(this, args);
        this.trigger.apply(this, ['route:' + name].concat(args));

        // ADDED BY: ManiKanta G
        // name: route method
        // fragment: route path
        // args: any additional args
        this.trigger.apply(this, ['route_change'].concat(name, fragment, args));
    }, this));
}

This will publish a common route_change event for every hashchange and passing the name, fragment, and other args using which I m highlighting the state all in a single place.

My question is do I have to override the Backbone method like this or is there any build in mechanism I can use here. If not, I would like to see similar behaviour in Backbone.js

Edit: sample program

Router = Backbone.Router.extend({
    routes : {
        '': 'root', 
        'home': 'home',
        'about':'about'
    },

    // app routing methods
    root: function () { console.log('root route');  },
    home: function () { console.log('home route');  },
    about: function () { console.log('about route'); }

});

Router.bind('all', function () {
    console.log('all route...');
});

router = new Router();

and, navigating using the above router:

router.navigate('home', true);

output: home route

Update on why the above program is not working:

we should bind for all event on Router instance, but not on the Router itself - so, changing the Router.bind('all', ... to router.bind('all', ...) will make the above program work

回答1:

In backbone 0.5.x you can bind all event to router instance and the first argument pass to your handler will be route

Here is exemple on jsfiddle, reproduced here:

var dummy = Backbone.Router.extend({
    defaultPage: 'messages',

    routes: {
        '': 'index',
        'index': 'index',
        'mailbox': 'mailbox'
    },

    index: function() {
        // code here
    },

    mailbox: function() {
        // code here
    }
});

var router = new dummy();

router.bind('all', function(route) {
    document.write('triggered: ' + route + '<br/>');
});

router.navigate('index', true);
router.navigate('mailbox', true);

回答2:

Here 's a live example from one of my apps:

routes.bind('all ', function(route, section) {
    var $el;
    route = route.replace('route: ', '');

    $el = $('#nav - ' + route);

    // If current route is highlighted, we're done.
    if ($el.hasClass('selected')) {
        return;
    } else {
        // Unhighlight active tab.
        $('#menu li.selected').removeClass('selected');
        // Highlight active page tab.
        $el.addClass('selected');
    }
});

回答3:

Here's what I'm doing:

@router.bind 'all', (route) ->
  # this triggers twice for every route; ignore the second time
  return if route == "route"

  # ex: route="route:home", name="home", href="#home"
  name = route.replace('route:', '')

  # remove the active class on all of the current nav links
  $("#menu li.active").removeClass('active')

  # add it back to the link that has an href that ends in `name`
  $("#menu a[href$='#{name}']").parent().addClass('active')

回答4:

I faced the problem that the first time a page is loaded, the menu wasn't highlighted as the event came before the binding was initiated. i fixed this by using the history:

$('#menu li.'+Backbone.history.fragment).addClass('active');