I have 5 drop down lists which is dynamic in nature. But the only problem is all the option values are being fetched from mysql database and i really want the user to know that the query is happening at the backend and he should wait by displaying a gif or a line saying "loading.. " .
I've been looking all over for this and similar questions have been posted by others but i don't seem to get it working . Please help me out. Can somebody please give a easy solution?
Thanks.
I've placed an example here:
http://jsfiddle.net/cMEaM/embedded/result/
I've kept as much of the existing code the same so you should still recognise it. The getXMLHTTP function is the same:
function getXMLHTTP() {
//function to return the xml http object
var xmlhttp = false;
try {
xmlhttp = new XMLHttpRequest();
} catch (e) {
try {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
try {
xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e1) {
xmlhttp = false;
}
}
}
return xmlhttp;
}
There's a new sendGet function to handle the XHR request, which takes success and error callbacks.
function sendGet(url, onSuccess, onError) {
var req = getXMLHTTP();
var method = "GET";
if (req) {
req.onreadystatechange = function() {
if (req.readyState == 4) {
// only if "OK"
if (req.status == 200) {
onSuccess(req);
} else {
onError(req);
}
}
}
req.open(method, url, true);
req.send(data);
}
}
I borrow a throbber from Wikipedia to display when the data is loading.
var throbberHtml = "<img src='http://upload.wikimedia.org/wikipedia/en/2/29/Throbber-Loadinfo-292929-ffffff.gif'>";
And these are the new getXXX functions which replace the <select> with the throbber while the data is loading:
function getState(countryId) {
var div = document.getElementById('statediv');
var oldInnerHTML = div.innerHTML;
var onSuccess = function(req) {
div.innerHTML = req.responseText;
};
var onError = function(req) {
div.innerHTML = oldInnerHTML;
alert("There was a problem while using XMLHTTP:\n" + req.statusText);
};
div.innerHTML = throbberHtml;
sendGet("findState.php?country=" + countryId, onSuccess, onError);
}
function getCity(countryId, stateId) {
var div = document.getElementById('citydiv');
var oldInnerHTML = div.innerHTML;
var onSuccess = function(req) {
div.innerHTML = req.responseText;
};
var onError = function(req) {
div.innerHTML = oldInnerHTML;
alert("There was a problem while using XMLHTTP:\n" + req.statusText);
};
div.innerHTML = throbberHtml;
sendGet("findCity.php?country=" + countryId + "&state=" + stateId,
onSuccess, onError);
}
There are other improvements that could be made, but I tried to keep in the sprit of your existing code as much as possible.
E.g. you can see that most of code in the getXXX functions is the same, so you could refactor these to use mostly the same code. Also, using a JS framework such as jQuery will replace the XHR code with better, more cross-browser compatible code. It's usually always better to avoid reinventing the wheel when it comes to code!
And you may possibly decide that sending the HTML for a <select> tag is not the best data format for the XHR. You might go with JSON which would decouple your presentation from the data.
Related
I'am trying to parse site. The site (i suppose) using scripts and data bases to load data from (dynamically?). And this is my problem... I am trying to grab data through C# (unfortunately i don't have access to code right now) or JS. And it seems like either C# and JS, get only template of the site, but don't wait until all scripts executed. So this is my question, is there any way to get ALL html source? Maybe call scripts somehow. Or make a request, wait for 10 seconds, and then write source html data into variable?
Here is my JS code.
function request(link)
{
var xhr = new XMLHttpRequest();
xhr.open('GET', link, true);
xhr.onreadystatechange = function() .
{console.log(xhr.readyState);};
xhr.send();
let data = xhr.responseText;
var tempDiv = document.createElement('div');
tempDiv.innerHTML = data.replace(/<script(.|\s)*?\/script>/g,
'');
return tempDiv;
}
function loadFile(url, timeout, callback)
{
var args = Array.prototype.slice.call(arguments, 3);
var xhr = new XMLHttpRequest();
xhr.ontimeout = function () {
console.error("The request for " + url + " timed out.");
};
xhr.onload = function() {
if (xhr.readyState === 4) {
if (xhr.status === 200) {
callback.apply(xhr, args);
} else {
console.error(xhr.statusText);
}
}
};
xhr.open("GET", url, true);
xhr.timeout = timeout;
xhr.send(null);
let data = xhr.responseText;
return data;
}
function showMessage (message) {
console.log(message + this.responseText);
}
function include(scriptUrl)
{
var xmlhttp = new XMLHttpRequest();
xmlhttp.open("GET", scriptUrl);
xmlhttp.onreadystatechange = function()
{
if ((xmlhttp.status == 200) && (xmlhttp.readyState == 4))
{
eval(xmlhttp.responseText);
}
};
xmlhttp.send();
let data = JSON.parse(xmlhttp.responseText);
var tempDiv = document.createElement('div');
tempDiv.innerHTML = data.replace(/<script(.|\s)*?\/script>/g,
'');
return tempDiv;
}
All this functions do not work as i want.
This isn't really practical - you're trying to load an HTML page, all associated scripts, then run them on the HTML page as if they were in a proper browser environment, but within your current browser session.
This sort of thing is feasible with the jsdom library if you were running on the server-side (NodeJS), because it simulates browser behaviour: https://github.com/jsdom/jsdom. So you could do
JSDOM.fromURL("https://example.com/", { runScripts: "dangerously" }).then(dom => {
console.log(dom.serialize()); //turn the page back into HTML
});
...to get the whole thing.
I am trying to figure out the best way to handle this scenario. Basically I want the flow to work like this:
1.) Get configuration data from server (async)
2.) Run doStuff() after configuration data is received (async)
3.) Run postResults after doStuff() completes
Currently I seem to have this flow working using PubSub.js, however I am trying to figure out how I can provide the results from config data (#1) to postResults (#3). While I seem to have the flow working with PubSub, I'm not sure how to access the configuration (#1) callback data from postResults (#3)
Here is a code summary:
PubSub.subscribe('config', doStuff());
fetchConfigurations();
function fetchConfigurations () {
var req = new XMLHttpRequest();
var url = CONFIGURATION_SERVER_URL;
req.onreadystatechange = function() {
if (req.readyState == 4 && req.status == 200) {
var configObject = eval('(' + req.responseText + ')');
PubSub.publish('config', configObject);
} else {
console.log("Requesting config from server: " + url);
}
}
req.open("GET", url, true);
req.send(null);
}
function doStuff() {
PubSub.subscribe('results', postResults);
var results = {};
// do some async work...
results['test1'] = "some message";
results['test2'] = "another message";
PubSub.publish('doStuff', results);
}
function postResults (doStuffId, doStuffData) {
var req = new XMLHttpRequest();
var url = TEST_RESULTS_URL; // I want to get this from the configObject is get in fetchConfigurations
req.open("POST",url,true);
req.setRequestHeader("Content-type","application/x-www-form-urlencoded");
req.send(doStuffData['test1'] + doStuffData['test2']);
}
Using promise seemed like the a better fit for this problem instead of pub/sub, here is the implementation I ended up using:
https://github.com/hemanshubhojak/PromiseJS
thanks in advance for your help! I am working with (and super new to) JavaScript, node.js with express, and sqlite3. I am trying to make an AJAX request to get a list of all the messages that have been posted to the chatroom page:
var meta = document.querySelector('meta[name=roomName]');
var roomName = meta.content;
window.addEventListener('load', function(){
var intervalID = setInterval(updateMessages, 4000);
}, false);
function updateMessages() {
var req = new XMLHttpRequest();
req.open('GET', '/' + roomName + '/messages.json', true);
req.send();
document.getElementById('messages').innerHTML = req.responseText;
}
Two questions: 1. I think I should be using setTimeout instead of setInterval. How would I go about switching to using this method? 2. Is the server-side code below that corresponds to the code above correct? How do I get access to the data that comes back after this request?
app.get('/:roomName/messages.json', function(request, response){
var roomName = request.params.roomName;
var sql = "SELECT ALL body FROM messages where room="+roomName+";";
conn.query(sql, function(error, result) {
if(error) {
console.log("There was an error.");
}
response.send(result);
});
});
setInterval is the appropriate thing to use here.
However, keep in mind that you will never see any messages because AJAX is asynchronous, so req.responseText won't have anything. You should use a readystatechange event:
req.open(......);
req.onreadystatechange = function() {
if( this.readyState == 4) {
document.getElementById('messages').innerHTML = this.responseText;
}
};
req.send();
I'm starting up playing with Win8 development and I'm stucked in a problem since yesterday.
I've followed the MSDN example HERE to grab the data, I can retrieve the data (therefore, isn't a connection limitation issue) but the problem is that regardless the settings I use, it always retrieve data as plain text, including \r\n characters.
I assume that if I could retrieve the structured XML would make my job easier, so I'm hoping you folks can put some lights on what I'm doing wrong.
Here's my code snippet:
<div id="xhrReport"></div>
<script>
var xhrDiv = document.getElementById("xhrReport");
xhrDiv.style.color = "#000000";
WinJS.xhr({ url: "http://www.w3schools.com/xml/note.xml", responseType: "responseXML"})
.done(
function complete(result) {
var xmlResponse = result.response;
xhrDiv.innerText = "Downloaded the page";
xhrDiv.style.backgroundColor = "#00FF00"; //here goes my breakpoint to check response value
},
function error(result) {
xhrDiv.innerHTML = "Got error: " + result.statusText;
xhrDiv.style.backgroundColor = "#FF0000";
},
function progress(result) {
xhrDiv.innerText = "Ready state is " + result.readyState;
xhrDiv.style.backgroundColor = "#0000FF";
}
);
</script>
Here's the value of xmlResponse
"<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>\r\n<!-- Edited by XMLSpy® -->\r\n<note>\r\n\t<to>Tove</to>\r\n\t<from>Jani</from>\r\n\t<heading>Reminder</heading>\r\n\t<body>Don't forget me this weekend!</body>\r\n</note>\r\n"
And HERE is a similar question, which seems to be working using the responseXML responseType (although it's not documented #MSDN guide).
Some things I already tried:
Use a responseType as 'document' (as per the MSDN guide) and then retrieve result.responseXML;
Omit the responseType argument;
Use the approach above.
Now, I ran out of ideas. Any thoughts?
Try To use the following code to get the tags you want to play... (I believe it will do exactly what you want/need, connecting to a webpage and than work on the result based o the webpage/xml tags
function connectToURL(){
var url = "";
xmlHttp = GetXmlHttpObject();
if (xmlHttp == null) {
return;
}
xmlHttp.onreadystatechange = stateChanged;
xmlHttp.open("GET", url,true);
xmlHttp.send(null);
}
// your job will actually start on this one...
function stateChanged() {
if(xmlHttp != null )
if (xmlHttp[item.key].readyState == 4 ) {
try {
var xmlDoc = xmlHttp.responseXML.documentElement.getElementsByTagName("TAGYOUWANTTOGET");
for (var i = 0; i < xmlDoc.length; i++) {
xmlDoc[i].getElementsByTagName("TAG")[0].childNodes[0].nodeValue
}
} catch (e) {
//work on the exception
}
}
}
}
function GetXmlHttpObject(){
var xmlHttp=null;
try{
xmlHttp = new XMLHttpRequest();
}
catch(e){
try{
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e){
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
}
return xmlHttp;
}
I think you should set an option for responseType : "document" just like:
WinJS.xhr({
url: "http://www.capital.bg/rss/?rubrid=" + groupId,
responseType:"document"
}).then(function (result) {
console.dir(result.response);
});
function getIDs() {
alert("1");
var title = document.getElementById('title').value;
alert(title);
title = "http://www.imdbapi.com/?i=&t=" + title;
alert(title);
xmlhttp=new XMLHttpRequest();
alert("2");
xmlhttp.open("GET",title,true);
alert("3");
xmlhttp.send();
alert("4");
var imdbData = xmlhttp.responseText;
alert(imdbData);
var imdbJSON = JSON.parse(imdbData);
//document.getElementById('title').value = imdbJSON.Title;
alert(imdbJSON.Title);
document.getElementById('imdbid').value = imdbJSON.ID;
return true;
}
I'm trying to fetch the ID of a film based upon it's title, the function gets called successfully and the alerts are correct until the alert which returns "imdbData", which returns a blank alert, then no more alerts occur, I'm unsure where I'm going wrong here. Any assistance would be appreciated.
You're opening it asynchronously. To make it synchronous, change this:
xmlhttp.open("GET",title,true);
To this:
xmlhttp.open("GET",title,false);
A usually-considered-better way would be to make it work with asynchronicity:
function getIDs() {
alert("1");
var title = document.getElementById('title').value;
title = "http://www.imdbapi.com/?i=&t=" + title;
xmlhttp=new XMLHttpRequest();
xmlhttp.onreadystatechange=function() {
if(xmlhttp.readyState==4) {
var imdbData = xmlhttp.responseText;
var imdbJSON = JSON.parse(imdbData);
document.getElementById('title').value = imdbJSON.Title;
document.getElementById('imdbid').value = imdbJSON.ID;
}
};
xmlhttp.open("GET",title,true);
xmlhttp.send();
return true;
}
Additionally, you cannot request pages from other domains. You may need to switch to JSONP if the API you're using supports it, or use your web server as a proxy.
You are not allowed to do cross site scripting with JavaScript which is why you get nothing in return.
You need to be on the same domain as you post your AJAX call to.
Use a serverside script to parse the URL for you instead.