If you’ve added some custom post types or taxonomies and you get 404 pages when trying to get to your new pages, you might need to remind WordPress that it needs to update its rules for handling URLs. Luckily, you can do this in one easy step with flush_rewrite_rules().
Just make sure it’s after your custom post type definitions and everything will sort itself out.
Sometimes you don’t want to create a named function in JavaScript just so that you can call it with setTimeout. And as Doug Crockford is always saying, eval is an evil thing.
To get anonymous functions to work with setTimeout or setInterval, you can use an the arguments object to call the anonymous function again.
(function () { // if you have a halting condition, add it here, otherwise run forever if (!some_halting_condition || run_forever) { // function code to go here as normal setTimeout(arguments.callee, 1000); } })();
It turns out that this is an amazingly useful pattern. Say you want a function to run every one second, but the function’s running time is actually two seconds. That’s not cool – so by using this pattern, the function will wait for a second after it has finished running, then call itself again.
jQuery uses a very similar pattern for (among other things, I’m sure) checking to see when the DOM has loaded in Internet Explorer by checking to see if the document body is scrollable.
Just a quick copy-paste of a custom taxonomy and post type for my site coasternerd. Currently, the site is built using categories creatively, but I thought it would be a nice exercise to rewrite it using the new features in WordPress 3.
It actually turns out that using these is much, much quicker than hacking around how categories are used to build various page types.
Won’t explain this today, but I wanted to make a note of it so that I can look back for example usage in the future.
/* to go inside functions.php * * Note: This will only work in WP3+! */ add_action ('init', 'register_custom_types'); function register_custom_types () { register_post_type ('rollercoaster', array ( 'label' => __('Roller coasters'), 'singular_label' => __('Roller coaster'), 'labels' => array ( 'not_found' => 'No coasters have been built yet!', 'add_new' => 'Build a coaster!', 'add_new_item' => 'Build a coaster!', 'edit_item' => 'Modify a coaster', 'new_item' => 'Build a coaster!', 'search_items' => 'Find a coaster' ), 'description' => 'List of roller coasters', 'public' => true, 'menu_position' => 4, 'supports' => array ('title', 'thumbnail', 'page-attributes', 'editor'), 'taxonomies' => array ('themepark'), 'publicly_queryable'=>true, 'rewrite'=>array("slug"=>"rollercoaster") )); register_taxonomy ('themepark', 'rollercoaster', array ( 'label' => 'Theme parks', 'labels' => array ( 'singular_name' => 'Theme park', 'search_items' => 'Find parks', 'popular_items' => 'Parks with most coasters', 'add_new_item' => 'Build a new park!', 'add_new' => 'Build a new park!', 'all_items' => 'All theme parks', 'edit_item' => 'Edit a park'), 'hierarchical' => false, 'publicly_queryable'=>true, 'public' => true, 'query_var' => 'themepark', 'rewrite'=>array('slug'=>'themepark') )); }
I noticed a very cool feature in WordPress today which lets you add thumbnail images to posts and pages. I used to do this with a custom field, but this makes it much, much easier.
Add this line to your theme’s functions.php
add_theme_support( 'post-thumbnails' );
When you write/edit a post, you’ll see a new box alongside Categories, Post Tags etc. From here, you can upload a thumbnail or choose one from the Media Library as you would for adding an image to a post.
Then inside your post templates, add this to display the thumbnail
the_post_thumbnail();
When I wanted a random number (more specifically integer), I used to do something like this (written in JavaScript):
1 2 | var highest = 3, random = Math.round ( Math.random () * (highest-1) + 1); |
Sounds good, right?
Wrong. Let’s try to make a random number between 1 and 3. It turns out that by using round, number 2 has a 50% chance of turning up with 1 and 3 having only a 25% chance.
1 can only be chosen if (Math.random * 2) + 1 returns something between 1 and 1.49; 2 will be chosen if the sum returns a number between 1.5 and 2.49; and 3 will be chosen if the returned number is between 2.5 and 3. You can see that the range for 2 is twice as big as 1 and 3.
The solution is to use Math.floor instead. This evens out the bias totally since 1 will be selected for numbers between 1 and 1.99, 2 will be returned for numbers between 2 and 2.99 and 3 will be chosen for values between 3 and 3.99. You can see that the interval between each of these ranges is now the same — so each number has the same probability of being chosen.
1 2 | var highest = 3, random = Math.floor ( Math.random () * highest + 1); |
Hint: ceil works just as well 
A lot of things on Linux seem pretty complicated, but a lot turn out to be pretty simple. To change the timezone:
1 2 | mv /etc/localtime /etc/localtime.default # just in case you need to restore it ln -sf /usr/share/zoneinfo/Europe/London /etc/localtime #obviously replacing Europe/London with your time zone |
Note: this was written for CentOS 5 – your system might vary
There are two parts to SSH keys – the public key and the private key. The public key is the one which you put onto the remote server, and the private key is the one you keep on your local machine. When you log in, some clever maths works on both to let you in.
ssh-keygenIt will ask you a couple of questions – just press enter to each one.
After it’s finished, it will have created two new files, ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub. The first is your private key – this is only for you and should stay on your local machine. The second is your public key – this is the one which needs to go onto your remote server.
scp ~/.ssh/id_rsa.pub username@hostname.com:~
Log into the remote machine then type these commands
cd ~ mv id_rsa.pub .ssh cd .ssh cat >> authorized_keys < id_rsa.pub rm id_rsa.pub
Now log out then log in again – you shouldn’t need to type the password this time. Magic.
I’ve wanted to play around with server-side JavaScript for a while now but never really been sure about how to go about it. Today, I took the dive.
First, I downloaded and installed node.js
1 2 3 4 5 | wget http://nodejs.org/dist/node-v0.1.33.tar.gz tar -xzvf node-v0.1.33.tar.gz && cd node-v0.1.33 ./configure make make install |
Next up is creating the classic Hello World first time app.
1 2 3 4 5 6 7 8 9 10 | var sys = require("sys"), http = require("http"); http.createServer(function(request, response) { response.sendHeader(200, {"Content-Type": "text/html"}); response.write("Hello World!"); response.close(); }).listen(8080); sys.puts("Server running at http://localhost:8080/"); |
Then start the server:
1 | node helloworld.js |
Go to http://localhost:8080/ and voila!
As a bonus, I’ve managed to get apache to route requests through to it (not sure if this is the best way to go about doing it…) Also remember that you need to start the JavaScript server first!
1 2 3 4 5 | <VirtualHost *:80> ServerName js.clintonmontague.co.uk RewriteEngine On RewriteRule ^/(.*)$ http://127.0.0.1:8080%{REQUEST_URI} [P,QSA,L] </VirtualHost> |
Now just to learn and write a decent JavaScript app!
I’ve installed the Firefox user agent switcher plugin. It lets you choose which user agent string you’d like to use to view a site with. Very useful if, for example, you’re developing an iPhone theme or you’d like to see how Googlebot will see your site.