I have the following generic Ajax response writer which I recently added some logic to, in order to dynamically parse the results for script objects, and run them when I find them using jQuery.globalEval().
Here is the code:
//Generic Results Writter method for Ajax Calls
function writeAjaxResponse(targetId, response) {
document.getElementById(targetId).innerHTML = response;
try {
var dom = $j(response);
dom.find('script').each( function(){
$j.globalEval(this.text || this.textContent || this.innerHTML || '');
});
} catch (e) {
console.error("Error parsing for script reloads: "+e);
}
}
This solution works very nicely the first time its called. However writeAjaxResponse(targetId, response); is called each time a user loads some dynamic Ajax content. And unfortunately after the first time, the scripts are no longer loaded. To be clear, after the server side generated page is loaded, there are numerous links on the page which the users may click, which invoke this handler for the Ajax response.
No error occurs, and no console.error() is written.. The Ajax data loads as normal, its just that the scripts in the response are no longer loaded.
In debugging, $j.globalEval is still getting called and this.text still has the script content in it, and the data looks correct, but still no joy.
Any light someone could shed on this would be very much appreciated!
Adding main ajax call for GET for reference:
function doAjaxGet(targetId, getUrl, handler) {`
var xmlhttp;
if (window.XMLHttpRequest) {
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp = new XMLHttpRequest();
} else {
// code for IE6, IE5
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
try {
handler(targetId, xmlhttp.response);
}
catch (err) {
alert("Failed calling handler, detail: " + err + " Got responseText: " + xmlhttp.responseText);
}
}
}
xmlhttp.open("GET", getUrl, true);
xmlhttp.send(null);
}
Related
I am ganging my head against the wall for 3 hours now. I have this code:
function showpctask() {
if (window.XMLHttpRequest) {
// code for IE7+, Firefox, Chrome, Opera, Safari
var xmlhttp = new XMLHttpRequest();
} else {
// code for IE6, IE5
var xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("pcactivitytask").innerHTML = xmlhttp.responseText;
}
};
xmlhttp.open("GET","showpctask.php"+,true);
xmlhttp.send();
}
that opens up a php file inside a div (id = pcactivitytask). That php file builds a 'select'
I also have this function right here:
function setpctaskwidth() {
var maxtaskwidth = 0;
$("div .pcactivitytask").each(function(){
c_width = parseInt($(this).width());
if (c_width > maxtaskwidth) {
maxtaskwidth = c_width;
}
});
alert (maxtaskwidth);
}
that will show me the max width of all elements with the the class of "pcactivitytask". Yes, the select created by the previous script has that class. If I call both these function it will NOT include the width of the NEWLY created select..... I need to run it AGAIN 'manuall'. I need my script to "onclick" BOTH build the NEW select AND include it in finding the max width by the second script. Thank you.
XMLhttprequest works asynchronously, meaning it does not happen in order.
that is why you have the xmlhttp.onreadystatechange callback function, that only runs once the request is finished
you do not specify how you call these two functions but I would expect to see the call to setpctaskwidth() inside the onreadystatechange function like this:
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("pcactivitytask").innerHTML = xmlhttp.responseText;
setpctaskwidth();
}
};
be advised that if the response includes images or other external resources (fonts etc) that don't already exist in the page you might get a different size than the actual final size (it will measure the size before the image is loaded)
I was wondering if it was possible to make a GET request with javascript, so it can update text without refreshing the page.
If this is possible, how can I make a get request with javascript & get the result/decode it from json?
I tried this from a past question:
function updateButton(){
var xmlHttp = null;
xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", "http://xxxx.com/getSpecialSale.php", false);
xmlHttp.send(null);
document.getElementById("dicebutton").innerHTML=xmlHttp.responseText;
}
And, it completely stops the main thread, making the website unresponsive. What is wrong?
Currently you set the async parameter to false, so the request is sent to the server and the browser waits for the response. To make an async request, just pass true as thrid param to open
xmlHttp.open("GET", "http://xxxx.com/getSpecialSale.php", true);
in addition to that, you have to register an callback, which waits for the response (and maybe to handle errors..)
xmlHttp.onload = function (e) {
if (xmlHttp.readyState === 4) {
if (xmlHttp.status === 200) {
console.log(xmlHttp.responseText);
} else {
console.error(xmlHttp.statusText);
}
}
};
xmlHttp.onerror = function (e) {
console.error(xmlHttp.statusText);
};
In addition to that a note from the mozilla docs
Note: Starting with Gecko 30.0 (Firefox 30.0 / Thunderbird 30.0 /
SeaMonkey 2.27), synchronous requests on the main thread have been
deprecated due to the negative effects to the user experience.
var isAjax=false;
function updateButton(){
if(!isAjax) { //Stops the user making a million requests per minute
isAjax=true;
var xmlHttp = null;
xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", "http://xxxx.com/getSpecialSale.php", true);
xmlHttp.send(null);
document.getElementById("dicebutton").innerHTML=xmlHttp.responseText;
isAjax=false;
}
}
OR jQuery...
$("#btnUpdate").click(function(){
$.get("http://xxxx.com/getSpecialSale.php", function(data, status){
$("#dicebutton").html(data);
});
});
If you want to use async you will need some code modifications, ie the stuff that happens after the response completes needs to be in a callback function as follows:
function updateButton(){
var xmlHttp = null;
xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", "http://xxxx.com/getSpecialSale.php", true);
xmlHttp.onload = function () {
document.getElementById("dicebutton").innerHTML=xmlHttp.responseText;
};
xmlHttp.send(null);
}
I understand that jQuery will not run when the DOM content is being loaded via AJAX. But I'm confused as to the reason why. My understanding was that the DOM elements didn't exist at the time the jQuery was initiated therefore it won't find the correct IDs or classes.
But I have a situation where the jQuery is only called AFTER all the content has been loaded via AJAX. yet it still does not work.
Here is my code. I am trying to get the function decorateGains() to run after AJAX completes.
loadData('7-days'); // Runs the default AJAX for 7 days
function loadData(type){
var xmlhttp;
if (window.XMLHttpRequest){xmlhttp=new XMLHttpRequest();}
else{xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200){document.getElementById("home-table").innerHTML=xmlhttp.responseText;}
}
xmlhttp.open("GET","actions/get-data-"+type+".php",true);
xmlhttp.send();
decorateGains();
}
You can see that I am including a call to the function decorateGains() right at the end of the loadData() function.
The decorateGains() function does run, as I can see my console message. However it does not do the task that it should.
function decorateGains() {
console.log('here');
$(".gains").each(function() {
var num = +($(this).text());
if (num > 0) {
console.log('here');
$(this).addClass("positive");
}
if (num < 0) {
console.log('here');
$(this).addClass("negative");
}
});
}
(The script searches for all elements with a class of .gains and adds a new class of positive or negative depending on the content of the element. Essentially it decorates the .gains element to be red or green depending on whether the number is negative or positive).
This is because the AJAX call is asynchronous. The request has not been completed (and therefore the new content has not been appended to the DOM) when you call your decorateGains() function. You need to place the call to the function inside the onreadystatechange handler, after setting the innerHTML:
loadData('7-days'); // Runs the default AJAX for 7 days
function loadData(type) {
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("home-table").innerHTML = xmlhttp.responseText;
decorateGains(); // <-- move this in here
}
}
xmlhttp.open("GET", "actions/get-data-" + type + ".php", true);
xmlhttp.send();
}
As we know that AJAX is used to request a web-part in HTML format from the server. Is it possible to request a script containing functions using AJAX?
Here's an example how to use eval() to accomplish what you need:
var xmlhttp;
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
eval(xmlhttp.responseText);
// you can use whatever functionw as returned from the server from this line on :)
}
}
xmlhttp.open("GET","your-server-page-url",true);
xmlhttp.send();
Yes you can load a javascript via ajax
http://api.jquery.com/jQuery.getScript/
$.getScript("ajax/test.js")
.done(function(script, textStatus) {
console.log( textStatus );
})
.fail(function(jqxhr, settings, exception) {
$( "div.log" ).text( "Triggered ajaxError handler." );
});
Also you could try something like this as mentioned in(how to run javascript in html loaded via ajax):
require("extra.js", function () {
functionDefinedInExtraJS();
});
//Sample require function:
function require(file, callback) {
var script = document.getElementsByTagName('script')[0],
newjs = document.createElement('script');
// IE
newjs.onreadystatechange = function () {
if (newjs.readyState === 'loaded' || newjs.readyState === 'complete') {
callback();
}
};
// others
newjs.onload = function () {
callback();
};
newjs.src = file;
script.parentNode.insertBefore(newjs, script);
}
One other way would be to use eval() function and convert a string reply into working javascript code.
Is it possible to request a script containing functions using AJAX?
Yes, it is possible. And those functions could be executed on the client. For example with jQuery you even have a function that allows you to perform such request: $.getScript.
I'm trying to fetch some content from another source using XHR as shown below:
function fetchPage(str)
{
if(str=="")
{
document.getElementById("table").innerHTML="";
resetFilters();
$('#progress').hide(); //fetching progress bar <div>
return;
}
if (window.XMLHttpRequest) // code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
else // code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
xmlhttp.onreadystatechange=postCallback;
xmlhttp.open("GET", "fetch.php?url=http://www.sis.itu.edu.tr/tr/ders_programlari/LSprogramlar/prg.php?fb="+str, true);
xmlhttp.send();
// any stuff that goes here will happen before callback
// (this is a good place to update a UI element showing a call is resolving.)
// (for example a spinner or text saying "fetching")
$('#progress').show();
progressFetching();
switch(xmlhttp.readyState){ //loading bar adjustments
case 0:
$('.bar').css("width","0%");
$('.bar').text("0%");
break;
case 1:
$('.bar').css("width","25%");
$('.bar').text("25%");
break;
case 2:
$('.bar').css("width","50%");
$('.bar').text("50%");
break;
case 3:
$('.bar').css("width","75%");
$('.bar').text("75%");
break;
}
}
function postCallback()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200){
progressDone(); //loading is finished
$('#error').hide();
document.getElementById("table").innerHTML=xmlhttp.responseText;
// continue to process post callback.
resetFilters();
}
else {
// report error with fetch
/*if(xmlhttp.status==404 || xmlhttp.responseText == "")
$('#error').show();*/
//$('#error').show();
}
}
I want my page to display error when connection timeout occurs, or when the computer doesn't have an internet connection (maybe a disconnection occurred while hanging around) or any other situation where the webpage fails to fetch the contents of the other source.
Using the code above, in the else block, if I go for if(xmlhttp.status==404 || xmlhttp.responseText == "") in the /* */ comment section, I won't get an error unless its not a 404 error. If i go for // comment section, error will be displayed after the fetching process is started until it is completed, i.e. between xmlhttp.readyState = 0 through xmlhttp.readyState = 4. How can I display connection error messages using these attributes or something else?
Thank your for your attention:)
According to this stackoverflow: XMLHttpRequest (Ajax) Error
xmlhttp.onreadystatechange = function (oEvent) {
if (xmlhttp.readyState === 4) {
if (xmlhttp.status === 200) {
console.log(xmlhttp.responseText)
} else {
console.log("Error", xmlhttp.statusText)
}
}
}
The problem is my template in prior question was flawed. I believe this will work better because it creates a closure to pass the variable you need to work with.
Once again, I did not test this so it might have typos and bugs -- nor did I change anything except how postCallback() is invoked and added a parameter to it.
function fetchPage(str)
{
if(str=="")
{
document.getElementById("table").innerHTML="";
resetFilters();
$('#progress').hide(); //fetching progress bar <div>
return;
}
var xmlhttp;
if (window.XMLHttpRequest) // code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
else // code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
xmlhttp.onreadystatechange=function () { postCallback(xmlhttp); };
xmlhttp.open("GET", "fetch.php?url=http://www.sis.itu.edu.tr/tr/ders_programlari/LSprogramlar/prg.php?fb="+str, true);
xmlhttp.send();
// any stuff that goes here will happen before callback
// (this is a good place to update a UI element showing a call is resolving.)
// (for example a spinner or text saying "fetching")
$('#progress').show();
progressFetching();
switch(xmlhttp.readyState){ //loading bar adjustments
case 0:
$('.bar').css("width","0%");
$('.bar').text("0%");
break;
case 1:
$('.bar').css("width","25%");
$('.bar').text("25%");
break;
case 2:
$('.bar').css("width","50%");
$('.bar').text("50%");
break;
case 3:
$('.bar').css("width","75%");
$('.bar').text("75%");
break;
}
}
function postCallback(xmlhttp)
{
if (xmlhttp.readyState==4 && xmlhttp.status==200){
progressDone(); //loading is finished
$('#error').hide();
document.getElementById("table").innerHTML=xmlhttp.responseText;
// continue to process post callback.
resetFilters();
}
else {
// report error with fetch
/*if(xmlhttp.status==404 || xmlhttp.responseText == "")
$('#error').show();*/
//$('#error').show();
}
}