There are some handy functions in PHP you would sometimes like to have in JavaScript, too. Why not reimplement them? It's not hard. Take for example in_array() and explode():
Hint: On many pages of PHP functions, there are comments which describe how to reimplement a function (e.g. PHP 4 implementations of PHP 5 functions) -- in PHP though, but it's easy to adapt them for JavaScript.
Here's a little trick how to print definitions of large arrays in a more beatiful way. Instead of passing a set of strings to the array() function, pass only one string to the explode() function!
For example, consider a section in the WordPress code (/wp-includes/post.php):
Not only is the second part shorter, but it is also easier to edit and to overview. Of course this always depends on how many elements your array has; it's rather ridiculous with small arrays.
JSON is a great data transfer format, especially for AJAX style applications (much better than XML for that purpose). Fetching JSON from your server is usually not a big deal these days, since all common browsers provide the XMLHttpRequest.
But: It can be a big problem to fetch data from a third party server, due to the Same Origin Policy. Imagine you want to provide a service where people simply need to include a JS file from your server to make great things happen on their own sites. Fetching JSON with your script via XMLHttpRequest (even from your own server) will not work.
However, there's a great workaround, which I first saw at Jeffrey Sambells' site. His solution is more generic, as it's able to load any JavaScript (not only JSON data) dynamically. Also, it's compatible with the XMLHttpRequest functions. I just needed something to fetch my JSON, and I don't need all of the XMLHttpRequest. Yet I do want to use AJAX indicators and error handling. So I used his code and taylored a lightweight JSON fetcher. If compressed with a JavaScript packer, it is as tiny as 1.4 kB.
The client side
Here's the code for the fetcher. Save it as request.js or something and have it loaded with your other JS. You can also insert into other JS files.
Of course, you need a part on the server to generate the dynamic parts. In this example, we simply output the date, but it can be any data that is expressible with a JSON string (and that's a lot). Save it as ajax.php in the same directory on the server.
A little demo to show you the integration into your own project. Save it as demo.html in the same directory as the other two, then load it in your browser.
What is a dynamic variable, or a variable variable, as they are sometimes called? When you create a variable, you give it a name. Consider this PHP example:
The first line will create the variable $foo and assign the string value 'test' to it. In the second line, the content of the variable $foo will be printed. So far, nothing exciting. But now consider this:
(Note the double $ sign at the beginning of the second line.) What happens here? First, the value 'foo' is assigned to the variable bar. In the second line, a variable is created, and this variable's name will be the content of the variable $bar. This means, the variable $foo is created. Hence, the third line will output testfoo. You can also have dynamic variables in arrays and objects, even as function aliases:
Here's a snippet of PHP code that can create passwords. It can create passwords of different lengths, it can use different sets (uppercase and lowercase letters as well as numbers), and it can be told to exclude potentially confusing characters.
Obviously, I wanted to place the Public Key for the account from one machine on the other one to append it to the authorized_keys file of the target account. Unfortunately, I didn't bear in mind that I already had a public key file (id_rsa.pub) in this directory. So I had to re-create the Public Key file from the Private Key. This is quite easy, it appears that the SSH developers already thought of this situation. The following code will restore the Public Key file from the Private Key (example for an RSA key):
If you have many databases with many write operations, it may be that the table overhead takes a good amount of space. (This is due to the fact that MySQL doesn't free the space of deleted entries.) With "optimizing" the tables, you can free that space.
Save the following script as /usr/local/sbin/optimizealltables.sh, make it chmod 700 (very important!), then replace YOURPASSWORD with your root MySQL password.
If you have have a select form element with a size attribute, one common option for the user is to leave it empty (especially in combination with multiple). The problem is, as soon as one or more options are selected, it is quite impossible in most browsers, to not select anything at all. And even if there is a way, it is not easy to accomplish. Try for yourself to deselect all items:
With a little JavaScript magic, we can offer a button to clear the select field:
