PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

864 Chapter 34 Building Web 2.0 Applications with Ajax
the current server time based on the 24-hour clock, and once as date('M d, Y'),
which returns the month, date, and year the script was called.
The result string itself will look like the following, with the items in brackets replaced
by the actual values:
It is [time] on [date].
In the next section, you’ll create the remaining function, theHTTPResponse(), and do
something with the response from the PHP script on the server.
Working with the Server Response
The getServerTime() function in the preceding section is ready to invoke
theHTTPResponse() and do something with the string that is returned.The following
example interprets the response and gets a string to display to the end user:
function theHTTPResponse() {
if (myReq.readyState == 4) {
if(myReq.status == 200) {
var timeString =
myReq.responseXML.getElementsByTagName("timestring")[0];
document.getElementById('showtime').innerHTML =
timeString.childNodes[0].nodeValue;
}
} else {
document.getElementById('showtime').innerHTML =
'';
}
}
The outer if…else statement checks the state of the object; if the object is in a state
other than 4 (completed), an animation is displayed ().
However, if myReq is in a readystate of 4, the next check is if the status from the server
is 200 (OK).
If the status is 200, a new variable is created: timeString.This variable is assigned the
value stored in the timestring element of the XML data sent from the server-side script,
which is retrieved by using the getElementByTagname method of the response from the
object:
var timeString = myReq.responseXML.getElementsByTagName("timestring")[0];