␡
- 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
Using JSON for Data (De)Serialization
var json = XMLHttp.responseText;
var book = eval("(" + json + ")");;
JSON is becoming more and more the de facto standard data exchange format for AJAX applications. Many AJAX frameworks support JSON, many Web Services provide a JSON interface, and PHP 6 will most probably feature JSON support at the core of the language.
Using JSON within JavaScript is quite simple, as well. The preceding code evaluates JSON and converts it into a JavaScript object—a simple eval() function call does the trick.
The JSON notation from the previous sidebar, "Understanding JSON," is stored in a file called phrasebook.json; then, the following code reads in this file using XMLHttpRequest and then outputs some data from it:
Using JSON for Data Deserialization (xmlhttpjson.html)
<script language="JavaScript"
type="text/javascript" src="xmlhttp.js"></script>
<script language="JavaScript"
type="text/javascript">
var XMLHttp = getXMLHttp();
XMLHttp.open("GET", "phrasebook.json");
XMLHttp.onreadystatechange = handlerFunction;
XMLHttp.send(null);
function handlerFunction() {
if (XMLHttp.readyState == 4) {
var json = XMLHttp.responseText;
var book = eval("(" + json + ")");
var pubdate = book.pubdate;
var title = book.title;
var publisher = book.publisher;
window.alert(title + " by " + publisher +
" (" + pubdate + ")");
}
}
</script>