Learning PHP, MySQL, JavaScript, and CSS, 2nd Edition

Bringing It All Together

The real beauty of PHP, MySQL, JavaScript, and CSS is the wonderful way in which they all work together to produce dynamic web content: PHP handles all the main work on the web server, MySQL manages all the data, and the combination of CSS and JavaScript looks after web page presentation. JavaScript can also talk with your PHP code on the web server whenever it needs to update something (either on the server or on the web page).

Without using program code, it’s a good idea at this point to summarize the contents of this chapter by looking at the process of combining our core technologies into an everyday Ajax feature that many websites use: checking whether a desired username already exists on the site when a user is signing up for a new account. A good example of this can be seen with Gmail (see Figure 1-3).

Figure 1-3. Gmail uses Ajax to check the availability of usernames

The steps involved in this Ajax process would be similar to the following:

1. The server outputs the HTML to create the web form, which asks for the necessary details, such as username, first name, last name, and email address.

2. At the same time, the server attaches some JavaScript to the HTML to monitor the username input box and check for two things: whether some text has been typed into it, and whether the input has been deselected because the user has clicked on another input box.

3. Once the text ...