Using the Hashtag

philostler edited this page Feb 29, 2012 · 2 revisions

Getting Started

The hashtag("#") is the original method of using PathJS. It is compatible with all modern browsers, and even some that are not-so-modern. To get started, all you need to do is define a route. A route can be any string prepended with a hash, such as:

#/my/first/route
#!/hashbang
#kittens

Binding Routes

PathJS provides the Path object. This is the root of the library, and is your gateway into route-defining heaven. You can define your routes like so:

// Use an anonymous function
Path.map("#/my/first/route").to(function(){
    alert("Hello, World!");
});

// Or define one and use it
function hello_world(){
    alert("Hello, World!");
}
Path.map("#/kittens").to(hello_world);

Aspect Oriented Programming

In addition to defining methods that will be executed when a route is activated, you can define methods that will be called before a route is activated, and after a route is left. This can be done via the enter and exit methods, respectively. They work exactly the same as the to method:

//Let's add an 'enter' method to one of our routes
Path.map("#/my/first/route").enter(function(){
    alert("Enter, minions!");
});

// You can also chain the methods together
Path.map("#!/hashbang/route").enter(fade_in).to(function(){
    alert("Method chaining is great!");
}).exit(fade_out);

Before Filters and Execution Halting

In some cases, you may want to perform multiple actions before an action is taken, and depending on their results, cancel the action altogether. For this reason, PathJS supports multiple 'enter' actions, which can be assigned individually or as an array:

Path.map("#/my/first/route").enter(function(){
    alert("First one!");
}).enter([
    function(){
        alert("Second!");
        return false;
    },
    function(){
        alert("And third!");
    }
]);

Path.map("#/my/first/route").to(function(){
    alert("Action!")
});

The methods are executed first-in-first-out, and if any of them returns false, the execution chain is immediately halted. In the example above, the third 'enter' method, as well as the actual action, will never get called, because the second one explicitly returns false.

Route Parameters

What good would a routing system be if it didn't allow you to use parameters? If you provide a route that contains a :token, that token will match anything, as long as the rest of the route matches as well. You can access the parameters inside your methods via the this.params object:

Path.map("#/users/:name").to(function(){
    alert("Username: " + this.params['name']);
});

The above route will match any of the following hrefs:

#/users/mike
#/users/27

Optional/Dynamic Routes

You can define a route that has optional components by wrapping the non-mandatory components in parentheses. Inside your bound method(s), any params that were not provided will come back as undefined.

Path.map("#/users(/:user_id)").to(function(){
    var user_id = this.params["user_id"] || "Set a default here!";
});

The above route will match both of the following:

#/users    // Your "user_id" parameter will be undefined.
#/users/7  // Your "user_id" parameter will be set to "7".

Root Route

If a user were to land on your page without a route defined, you can force them to use a root route. This route will be automatically selected on page load:

Path.root("#/home");

Rescue Method

If a route somehow ended up in your system without being properly bound to an action, you can specify a "rescue" method that will be called. This lets you provide instant user feedback if they click an undefined route:

Path.rescue(function(){
    alert("404: Route Not Found");
});

Automatic Dispatching

If a user gets to your page with an already defined route (for example, the click a referral link with the href of "www.yoursite.com/media#download"), PathJS will automatically find and execute the appropriate route methods.

Listen Carefully

You can define routes all day long, but if you don't tell us to listen for them, nothing's going to happen. Once you've got your routes defined, start the listener up by simply typing:

Path.listen();

You should always wrap your Path.listen() statements in some form of "Document Ready" method. This prevents errors when users come to your site with a predefined route. Without knowing the DOM is completely done loading, that route will be executed, and may try to perform operations it won't yet have the ability to do.