http://llmotorsport.se/resources/scripts/jsr_class.js

1// jsr_class.js
2//
3// JSONscriptRequest -- a simple class for making HTTP requests
4// using dynamically generated script tags and JSON
5//
6// Author: Jason Levitt
7// Date: December 7th, 2005
8//
9// A SECURITY WARNING FROM DOUGLAS CROCKFORD:
10// "The dynamic <script> tag hack suffers from a problem. It allows a page 
11// to access data from any server in the web, which is really useful. 
12// Unfortunately, the data is returned in the form of a script. That script 
13// can deliver the data, but it runs with the same authority as scripts on 
14// the base page, so it is able to steal cookies or misuse the authorization 
15// of the user with the server. A rogue script can do destructive things to 
16// the relationship between the user and the base server."
17//
18// So, be extremely cautious in your use of this script.
19//
20//
21// Sample Usage:
22//
23// <script type="text/javascript" src="jsr_class.js"></script>
24// 
25// function callbackfunc(jsonData) {
26//      alert('Latitude = ' + jsonData.ResultSet.Result[0].Latitude + 
27//            '  Longitude = ' + jsonData.ResultSet.Result[0].Longitude);
28//      aObj.removeScriptTag();
29// }
30//
31// request = 'http://api.local.yahoo.com/MapsService/V1/geocode?appid=YahooDemo&
32//            output=json&callback=callbackfunc&location=78704';
33// aObj = new JSONscriptRequest(request);
34// aObj.buildScriptTag();
35// aObj.addScriptTag();
36//
37//
38
39
40// Constructor -- pass a REST request URL to the constructor
41//
42function JSONscriptRequest(fullUrl) {
43    // REST request path
44    this.fullUrl = fullUrl; 
45    // Keep IE from caching requests
46    this.noCacheIE = '&noCacheIE=' + (new Date()).getTime();
47    // Get the DOM location to put the script tag
48    this.headLoc = document.getElementsByTagName("head").item(0);
49    // Generate a unique script tag id
50    this.scriptId = 'JscriptId' + JSONscriptRequest.scriptCounter++;
51}
52
53// Static script ID counter
54JSONscriptRequest.scriptCounter = 1;
55
56// buildScriptTag method
57//
58JSONscriptRequest.prototype.buildScriptTag = function() {
59
60    // Create the script tag
61    this.scriptObj = document.createElement("script");
62
63    // Add script object attributes
64    this.scriptObj.setAttribute("type", "text/javascript");
65    this.scriptObj.setAttribute("charset", "utf-8");
66    this.scriptObj.setAttribute("src", this.fullUrl + this.noCacheIE);
67    this.scriptObj.setAttribute("id", this.scriptId);
68};
69 
70// removeScriptTag method
71//
72JSONscriptRequest.prototype.removeScriptTag = function() {
73    // Destroy the script tag
74    this.headLoc.removeChild(this.scriptObj);
75};
76
77// addScriptTag method
78//
79JSONscriptRequest.prototype.addScriptTag = function() {
80    // Create the script tag
81    this.headLoc.appendChild(this.scriptObj);
82};