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URL Mapping Library for client-side and server-side JS

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README.md

RouteMap.js

URL Mapping Library for client-side and server-side JS

See JSDoc documentation.

RouteMap maps URL patterns to methods. It is written in "plain old" JavaScript and can be used in conjunction with any other libraries. It does, however, require JavaScript 1.8 Array methods (such as map, filter, reduce, etc.). If these methods do not exist, it will throw an error. Reference implementations of these errors can be added to any environment to back-port these functions if they don't already exist.

In the browser, the typical use case is for mapping URL fragments (window.location.hash) to JavaScript methods. By default, RouteMap.handler is not associated with any event. If the environment it will be used in supports a window onhashchange event, then binding RouteMap.handler to it will work out of the box. If not, a simple URL polling function can be used instead. Similarly, if the environment supports the HTML5 history API, the onpopstate event can be bound.

Hashbang (#!)

The URL patterns RouteMap uses are based on a file-system path analogy, so all patterns must begin with a '/' character. In order to support the hashbang convention, even though all URL patterns must begin with '/', a prefix can be specified. The default prefix value is '#' but if you want your site to be indexed, you can switch the prefix to be '#!':

RouteMap.prefix('#!');

Directives

Routes added to RouteMap can be static URLs, or they can have dynamic components that get parsed and passed into their respective methods inside an arguments dictionary. There are three basic types of directives:

(a) unnamed

Consider the rule:

RouteMap.add({route: '/users/:id', method: 'users.get'});

:id can be any scalar value as long as it does not contain a '/' character. So for example, the URL: /users/45 would cause users.get to be invoked with one argument: {id: '45'}

An unnamed token can be followed by a '?' character to indicate it is optional, but no other unnamed parameter can follow an optional unnamed parameter, because that would lead to ambiguous URLs:

RouteMap.add({route: '/users/:id/:fave?',           method: 'users.get'}); // works
RouteMap.add({route: '/users/:id/:fave?/:other',    method: 'users.get'}); // throws an error
RouteMap.add({route: '/users/:id?/:fave?/:other',   method: 'users.get'}); // also throws an error

(b) named

Named tokens of rule expressions are different from unnamed tokens in that they can appear anywhere in a URL. Because they are key/value pairs, their order can be arbitrary. Here is an example:

RouteMap.add({route: '/users/id:', method: 'users.get'});

Notice that the colon comes after the token name id. A matching URL for this rule would look like: /users/id=45

RouteMap will automatically URL encode/decode values when generating URLs and parsing them.

(c) star

Star directives act like a sieve. Normally, if a URL matches a pattern but has extraneous parameters, then it is not considered a match and RouteMap will not fire that pattern's handler. But if a star directive exists at the end of the rule, like in these examples:

RouteMap.add({route: '/users/id:/*',        method: 'users.get'});
RouteMap.add({route: '/users/id:/extras:*', method: 'users.get_two'});

Then URLs with extraneous information like /users/45/something_else/goes=here will still match. In the case of the rules above, the following function calls will fire:

users.get({id: '45', '*': '/something_else/goes=here'});
users.get_two({id: '45', extras: '/something_else/goes=here'});

However, star directives are not exactly wildcards, they may not preserve the order of the extraneous items in a URL. They will always put all of the unnamed extra pieces of a URL before the named pieces. So if the URL /users/45/goes=here/something_else is accessed, the arguments will still be exactly as they are above.

Client-Side Sample

In a browser environment RouteMap can be used as is. Here are some samples:

<script type="text/javascript" src="/path/to/jquery.js"></script>
<script type="text/javascript" src="/path/to/routemap.js"></script>
// assumes jQuery exists and we are using a modern(ish) browser that supports onhashchange
// but jQuery is not necessary to use RouteMap, just shown here for event handling
$(function () {
    var routes = window.RouteMap, rules, rule;
    // add some rules
    rules = {
        load_main:      {route: '/',        method: 'load'},
        load_foo_main:  {route: '/foo',     method: 'load_foo_main'},
        load_foo:       {route: '/foo/:id', method: 'load_foo'}
    };
    for (rule in rules) if (rules.hasOwnProperty(rule)) routes.add(rules[rule]);
    // set up window listener and initial fire
    $(window).bind('hashchange', routes.handler);
    $(routes.handler); // in addition to binding hash change events to window, also fire it onload
});

The previous example assumes that load_main, load_foo_main, and load_foo all exist in the global (window) object:

window.load_main        = function (args) {
    // do some work (args is an empty object)
};
window.load_foo_main    = function (args) {
    // do some work (args is an empty object)
};
window.load_foo         = function (args) {
    // do some work (args is an object that has 'id' in it)
};

Typically, you may not want to pollute the global namespace, so RouteMap allows changing the context in which it looks for rules' methods. The above examples could, for example work like this:

// assumes jQuery exists and we are using a modern(ish) browser that supports onhashchange
// however, we could be using any other library (or no library!) and we could create a hash polling function, etc.
$(function () {
    var routes = window.RouteMap, rules, rule;
    // add some rules
    rules = {
        load_main:      {route: '/',        method: 'load_main'},
        load_foo_main:  {route: '/foo',     method: 'load_foo_main'},
        load_foo:       {route: '/foo/:id', method: 'load_foo'}
    };
    routes.context({
        load_main:      function (args) {/* do some work (args is an empty object) */},
        load_foo_main:  function (args) {/* do some work (args is an empty object) */},
        load_foo:       function (args) {/* do some work (args is an object that has 'id' in it) */}
    });
    for (rule in rules) if (rules.hasOwnProperty(rule)) routes.add(rules[rule]);
    // set up window listener and initial fire
    $(window).bind('hashchange', routes.handler);
    $(routes.handler); // in addition to binding hash change events to window, also fire it onload
});

The method attribute of each rule can drill down arbitrarily deep (e.g., 'foo.bar.baz') into the context object and as long as that index exists, RouteMap will fire the correct function when a URL matching that pattern is called.

Server-Side Sample

In a server-side setting like Node.js, RouteMap can be imported using require. Because the client-side functionality does not distinguish between different HTTP requests (GET, POST, HEAD, etc.), the server-side version will likely need a dispatcher function if you need to distinguish between different request types. The example below shows a server that will answer GET requests to / and /bar/ + {an ID string} and POST requests to /foo. It will return a not-found message to all other requests (by overwriting RouteMap.default_handler). Note that the RouteMap.handler function is passed the request and response objects, which means they get passed into each listener as additional parameters after the args object.

var http = require('http'), routemap = require('./routemap').RouteMap, PORT = 8124;
(function () {
    var listeners, dispatch, rules, rule;
    listeners = {
        main: {
            get: function (args, request, response) {
                response.writeHead(200, {'Content-Type': 'text/plain'});
                response.write('GET / happened\n');
            }
        },
        foo: {
            post: function (args, request, response) {
                response.writeHead(200, {'Content-Type': 'text/plain'});
                response.write('POST /foo happened\n');
            }
        },
        bar: {
            get: function (args, request, response) {
                response.writeHead(200, {'Content-Type': 'text/plain'});
                response.write('here is bar[' + args.id + ']\n');
            }
        }
    };
    dispatch = function (listener) {
        return function (args, request, response) {
            var method = request.method.toLowerCase();
            if (listeners[listener] && listeners[listener][method])
                listeners[listener][method](args, request, response);
            else
                routemap.default_handler(request.url, request, response);
        };
    };
    rules = {
        main:   {route: '/',        method: 'main.handler', handler: dispatch('main')},
        foo:    {route: '/foo',     method: 'foo.handler',  handler: dispatch('foo')},
        bar:    {route: '/bar/:id', method: 'bar.handler',  handler: dispatch('bar')}
    };
    // set up routemap
    routemap.context(rules); // where routemap looks for the methods specified
    for (rule in rules) routemap.add(rules[rule]);
    routemap.default_handler = function (url, request, response) {
        response.writeHead(404, {'Content-Type': 'text/plain'});
        response.write('Sorry!\n' + request.method + ' ' + request.url + ' does not work');
    };
})();
http.createServer(function (request, response) {
    routemap.get = function () {return request.url;};
    routemap.handler(request, response);
    response.end();
}).listen(PORT, '127.0.0.1');
console.log('HTTP listening on port ' + PORT + '\nCTRL-C to bail');

Tests

To run the tests in a browser, open: ./tests/tests-browser.html

To run the tests in node, run: node ./tests/tests-node.js

© 2011 OpenGamma Inc. and the OpenGamma group of companies

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