// jsr_class.js
//
// JSONscriptRequest -- a simple class for making HTTP requests
// using dynamically generated script tags and JSON
//
// Author: Jason Levitt
// Date: December 7th, 2005
//
// A SECURITY WARNING FROM DOUGLAS CROCKFORD:
// "The dynamic <script> tag hack suffers from a problem. It allows a page 
// to access data from any server in the web, which is really useful. 
// Unfortunately, the data is returned in the form of a script. That script 
// can deliver the data, but it runs with the same authority as scripts on 
// the base page, so it is able to steal cookies or misuse the authorization 
// of the user with the server. A rogue script can do destructive things to 
// the relationship between the user and the base server."
//
// So, be extremely cautious in your use of this script.
//
// Sample Usage:
//
// <script type="text/javascript" src="jsr_class.js"></script>
// 
// function callbackfunc(jsonData) {
//      alert('Latitude = ' + jsonData.ResultSet.Result[0].Latitude + 
//            '  Longitude = ' + jsonData.ResultSet.Result[0].Longitude);
//      aObj.removeScriptTag();
// }
//
// request = 'http://api.local.yahoo.com/MapsService/V1/geocode?appid=YahooDemo&
//            output=json&callback=callbackfunc&location=78704';
// aObj = new JSONscriptRequest(request);
// aObj.buildScriptTag();
// aObj.addScriptTag();
//
function JSONscriptRequest(fullUrl){this.fullUrl=fullUrl;this.noCacheIE='&noCacheIE='+(new Date()).getTime();this.headLoc=document.getElementsByTagName("head").item(0);this.scriptId='JscriptId'+JSONscriptRequest.scriptCounter++;}
JSONscriptRequest.scriptCounter=1;JSONscriptRequest.prototype.buildScriptTag=function(){this.scriptObj=document.createElement("script");this.scriptObj.setAttribute("type","text/javascript");this.scriptObj.setAttribute("charset","utf-8");this.scriptObj.setAttribute("src",this.fullUrl+this.noCacheIE);this.scriptObj.setAttribute("id",this.scriptId);}
JSONscriptRequest.prototype.removeScriptTag=function(){this.headLoc.removeChild(this.scriptObj);}
JSONscriptRequest.prototype.addScriptTag=function(){this.headLoc.appendChild(this.scriptObj);}