Node.js url.parse result back to string - url

Question

I am trying to do some simple pagination.
To that end, I'm trying to parse the current URL, then produce links to the same query, but with incremented and decremented page parameters.
I've tried doing the following, but it produces the same link, without the new page parameter.
var parts = url.parse(req.url, true);
parts.query['page'] = 25;
console.log("Link: ", url.format(parts));
The documentation for the URL module seems to suggest that format is what I need but I'm doing something wrong.
I know I could iterate and build up the string manually, but I was hoping there's an existing method for this.

Answer 1

If you look at the latest documentation, you can see that url.format behaves in the following way:
search will be used in place of query
query (object; see querystring) will only be used if search is absent.
And when you modify query, search remains unchanged and it uses it. So to force it to use query, simply remove search from the object:
var url = require("url");
var parts = url.parse("http://test.com?page=25&foo=bar", true);
parts.query.page++;
delete parts.search;
console.log(url.format(parts)); //http://test.com/?page=26&foo=bar
Make sure you're always reading the latest version of the documentation, this will save you a lot of trouble.

Answer 2

Seems to me like it's a bug in node. You might try
// in requires
var url = require('url');
var qs = require('querystring');
// later
var parts = url.parse(req.url, true);
parts.query['page'] = 25;
parts.query = qs.stringify(parts.query);
console.log("Link: ", url.format(parts));

Answer 3

The other answer is good, but you could also do something like this. The querystring module is used to work with query strings.
var querystring = require('querystring');
var qs = querystring.parse(parts.query);
qs.page = 25;
parts.search = '?' + querystring.stringify(qs);
var newUrl = url.format(parts);

Answer 4

To dry out code and get at URL variables without needing to require('url') I used:
/*
Used the url module to parse and place the parameters into req.urlparams.
Follows the same pattern used for swagger API path variables that load
into the req.params scope.
*/
app.use(function(req, res, next) {
var url = require('url');
var queryURL = url.parse(req.url, true);
req.urlparams = queryURL.query;
next();
});
var myID = req.urlparams.myID;
This will parse and move the url variables into the req.urlparams variable. It runs early in the request workflow so is available for all expressjs paths.