Java Reference
In-Depth Information
The first few lines of code define the requestSuccess() and requestFailed() functions. These
functions accept a parameter called transport —a special object that contains the server's response
(more on this later).
After the function definitions, you create an options object that contains properties for the
HTTP method option, the onSuccess option, and the onFailure option. Then, you finally make
the request for the someTextFile.txt file, passing the options object to the Ajax.Request()
constructor (don't forget the new keyword!).
If you need to send parameters with your request, you'll have to do a bit more preparation before
calling new Ajax.Request() . Like jQuery, you can create an object to contain the parameter names
and values. For example, if you need to send a parameter called username with your request, you
can do something like this:
var parms = {
username: "jmcpeak"
};
 
options.parameters = parms;
When you send the request by creating a new Ajax.Request object, the parameters are added to the
URL before the request is sent to the server.
All callback functions are passed a parameter containing an Ajax.Response object, an object
that wraps around the native XMLHttpRequest object. It contains a variety of useful properties
for working with the server's response. It emulates the basic properties of XMLHttpRequest , such
as readyState , responseText , responseXML , and status . But it also exposes a few convenience
properties, as outlined in the following table.
propertY name
purpose
The Ajax.Request object used to make the request
request
A parsed JSON structure if the response's Content‐Type header is
application/json
responseJSON
The HTTP status text sent by the server
statusText
The native XMLHttpRequest object used to make the request
transport
Now that you've been given a crash course in Prototype's Ajax functionality, let's modify the Ajax
Form Validator.
revisiting the Form Validator with prototype
trY it out
Open your text editor and type the following:
<!DOCTYPE html>
 
<html lang="en">
<head>
<title>Chapter 17: Example 4</title>
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