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At the Forge - Prototype

Issue 153

From Issue #153
January 2007

Jan 01, 2007  By Reuven M. Lerner
 in
Prototype eases the burden of using JavaScript in Ajax.

Listing 5. ajax-register-prototype.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head><title>Register</title>

    <script type="text/javascript" src="prototype.js"></script>
    <script type="text/javascript">
        function parseResponse(originalRequest) {

            var warning = $("warning");
            var submit_button = $("submit-button");

        switch (originalRequest.responseText)
        {
        case "yes":
            Element.update(warning,
                           "Username '" + $F("username") +"' is taken!");
            submit_button.disabled = true;
            break;

        case "no":
            Element.update(warning, "");
            submit_button.disabled = false;
            break;

        case "":
            break;

        default:
            alert("Unexpected response '" +
                                originalRequest.responseText + "'");
            }
        }

        function checkUsername()
        {
        var url =
"http://maps.lerner.co.il/cgi-bin/check-name-exists.pl";

        var myAjax = new Ajax.Request(
        url,
        {
        method: 'get',
        parameters: "username=" + $F("username"),
        onComplete: parseResponse
            }
            );
        }

    </script>
  </head>
  <body>
    <h2>Register</h2>
    <p id="warning"></p>
    <form action="/cgi-bin/register.pl" method="post"
enctype="application/x-www-form-urlencoded">
        <p>Username: <input type="text" id="username" name="username"
onchange="checkUsername()" /></p>
        <p>Password: <input type="password" name="password" /></p>
        <p>E-mail address: <input type="text" name="email_address" /></p>
        <p><input type="submit" value="Register" id="submit-button"
/></p>
    </form>
  </body>
</html>
Conclusion

Several months ago, I remarked in this column that I don't very much like JavaScript. Although there still are elements of the language that I dislike, Prototype has done wonders to change my attitude toward the language. I no longer feel as bogged down in verbose syntax. Prototype has provided me with a feeling of liberation, and I'm able to concentrate on higher-level functionality rather than iterating through hierarchies of nodes or worrying about cross-browser compatibility. With a bit of practice, you also might find Prototype to be the antidote for anti-JavaScript feelings.

What's more, Prototype now sits at the base of a stack of different JavaScript libraries, such as Scriptaculous and Rico. In the coming months, we will look at what these libraries can do for your Web development, including Ajax development. We will then look at some alternatives to Prototype, which also have a great deal to offer the aspiring Ajax programmer.

Resources for this article: /article/9455.

Reuven M. Lerner, a longtime Web/database consultant, is a PhD candidate in Learning Sciences at Northwestern University in Evanston, Illinois. He currently lives with his wife and three children in Skokie, Illinois. You can read his Weblog at altneuland.lerner.co.il.

______________________

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