Some experiments with web applications
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// variable to en-/disable debug
// set to 1 to enable debug log
var DEBUG = 1;
// xmlhttp object function
function getHTTPObject() {
// debug log
if (DEBUG === 1) {console.log("xml http object function");}
// variable definitions
var xhr;
// check for availibility if xmlhttprequest object
if(window.XMLHttpRequest) {
xhr = new XMLHttpRequest();
} else if(window.ActiveXObject) {
xhr = new ActiveXObject("Msxml2.XMLHTTP");
}
return xhr;
}
// ajax call function
function ajaxCall(dataUrl, outputElement, callback, responseType) {
// debug log
if (DEBUG === 1) {console.log("ajax function");}
// variable definitions
var response,
request = getHTTPObject(); // get the xmlhttp object which is supported
outputElement.innerHTML = "Lade Daten ...";
request.onreadystatechange = function() {
if(request.readyState === 4 && request.status === 200) {
//save ajax response
if (responseType === "json") {
response = JSON.parse(request.responseText);
} else if (responseType === "xml") {
response = request.responseXML;
} else {
response = request.responseText;
}
// check if callback is a function
if(typeof callback === "function") {
callback(response);
}
}
};
request.open("get", dataUrl, true);
request.send(null);
}
// wrap all in anonymous function to get out of global scope
(function() {
//variable definitions
var serverUrl, // this will hold the url we call with the ajaxCall() function
target = document.getElementById("output"), // get the html area where we print out the data
searchForm = document.getElementById("search-form"), // get the search form
haltestelle; // object with methods to get and process the data
// debug log
if (DEBUG === 1) {console.log("anonymous function");}
// parse actual url and parse for protocol type (http/https)
// set the ajax server url dependent on the protocol
// for strato ssl-proxy, we have to insert the 1st part of the url path
serverUrl = window.location.protocol + "//" + window.location.hostname;
if (serverUrl.indexOf("https") === -1) {
serverUrl += "/cgi-bin/";
} else {
serverUrl += "/" + window.location.pathname.split("/")[1] + "/cgi-bin/";
}
// haltestelle object
haltestelle = {
getAbfahrten : function (event) {
// debug log
if (DEBUG === 1) {console.log("getAbfahrten() method");}
// prevent submit default behaviour
event.preventDefault();
// construct ajax url
var hstName = document.getElementById("q").value,
hstUrl = encodeURI(serverUrl + "abfahrtsmonitor.py?query=abfahrten.do&ort=dresden&hst=" + hstName);
// get the data from the server with an ajax call
ajaxCall(hstUrl, target, haltestelle.processAbfahrten, "text");
},
processAbfahrten : function (data) {
// debug log
if (DEBUG === 1) {console.log("processAbfahrten() method");}
if (DEBUG === 1) {console.log("received data: " + data);}
//variable definitions
var i,
y,
htmlOutput,
entry,
dataLength;
// process of response only if it's not empty
if (data.indexOf("[]") === -1) {
// replace useless chars & split string into array
data = data.replace(/\],\[/gi, '#'); // insert a special char to mark internal array boundaries
data = data.replace(/\(.+?\)/gi, ''); // remove all content in round parentheses
data = data.replace('ß', 'ss'); // remove some special characters
data = data.replace(/<(.+?)>/gi, '$1'); // remove tag parentheses to prevent code injection
data = data.slice(3,-3).split("#"); // split on the inserted char to get an array of arrays
// debug log
if (DEBUG === 1) {console.log("parsed data: " + data);}
dataLength = data.length;
// generate table header
htmlOutput = "<table>";
htmlOutput += "<tr>";
htmlOutput += "<th>Linie</th>";
htmlOutput += "<th>Richtung</th>";
htmlOutput += "<th>Abfahrt</th>";
htmlOutput += "</tr>";
// generate table entries
for (i = 0; i < dataLength; i++) {
htmlOutput += "<tr>";
entry = data[i].split(",");
// debug log
if (DEBUG === 1) {console.log("part " + i + " of parsed data: " + entry);}
for (y = 0; y < 3; y++) {
// debug log
if (DEBUG === 1) {console.log("part " + y + ": " + entry[y]);}
htmlOutput += "<td>" + entry[y].slice(1,-1) + "</td>";
}
htmlOutput += "</tr>";
}
// close table
htmlOutput += "</table>";
} else { // there was an empty response
htmlOutput = "<p>Haltestelleneingabe nicht eindeutig</p>";
}
// print content into web page
target.innerHTML = htmlOutput;
},
getHaltestellen : function (event) {
// debug log
if (DEBUG === 1) {console.log("getHaltestellen() method");}
// prevent submit default behaviour
event.preventDefault();
// construct ajax url
var hstName = document.getElementById("q").value,
hstUrl = encodeURI(serverUrl + "abfahrtsmonitor.py?query=haltestelle.do&ort=dresden&hst=" + hstName);
// get the data from the server with an ajax call
ajaxCall(hstUrl, target, haltestelle.processHaltestellen, "text");
},
processHaltestellen : function (data) {
// debug log
if (DEBUG === 1) {console.log("processHaltestellen() method");}
if (DEBUG === 1) {console.log("received data: " + data);}
}
};
//event listeners
searchForm.addEventListener("submit", haltestelle.getAbfahrten, false);
searchForm.addEventListener("submit", haltestelle.getHaltestellen, false);
}()); // end of anonymous function