JavaScript router

Question:

I couldn't understand the function respond in below code snippet .

How can it know req.params.name from '/hello/:name' ?

var restify = require('restify');
function respond(req, res, next) {
    res.send('hello ' + req.params.name);
}
var server = restify.createServer();
server.get('/hello/:name', respond);
server.head('/hello/:name', respond);
server.listen(8080, function() {
    console.log('%s listening at %s', server.name, server.url);
});

Link: http://www.joyent.com/developers/getting-started-node-js

Answer:

It is handled automatically by a router. Everything after a ":" is consider a param, and will be put into req.params.XXX by router. Different framework has different router. But it is always follow the similar rule: If you define a route like in this code '/hello/:abc', then a real route '/hello/:charlie" will cause params.abc -> charlie

I guess, in your case, you are using Node express as router. So you can check out Express's router function, how it is parse the URL. I am using Metoer.js's iron router, all of them should be doing the same thing.

- Kevin Zhang