␡
- Initializing an AJAX Application
- Sending a GET Request
- Sending a POST Request
- Sending a Synchronous Request
- Receiving Multiple Data from the Server
- Aborting an HTTP Request
- Retrieving HTTP Headers
- Receiving XML from the Server
- Using JSON for Data (De)Serialization
- Creating a Waiting Screen
- Solving the Bookmark Problem
- Solving the Back Button Problem
- Using XSLT
- Using an XML Library
- Using the Yahoo! Web Service
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
Sending a Synchronous Request
XMLHttp.open("GET", "phrasebook.txt", false);
By default, HTTP requests via XMLHttpRequest are asynchronous, which explains the need for a callback function. However, when you set the third parameter of the open() method to false, the request is a synchronous one, which means that the script execution is stopped until data comes back from the server. The following code makes use of that:
Sending a Synchronous Request (xmlhttpsync.html)
<script language="JavaScript"
type="text/javascript" src="xmlhttp.js"></script>
<script language="JavaScript"
type="text/javascript">
window.onload = function() {
var XMLHttp = getXMLHttp();
XMLHttp.open("GET", "phrasebook.txt", false);
XMLHttp.send(null);
document.getElementById("output").innerHTML =
"Returned data: " + XMLHttp.responseText;
}
</script>
<p id="output">Calling the server ...</p>
Note that the whole code is executed only after the full page has been loaded; otherwise, the access to the output HTML element may fail.