We Keep Coding

JavaScript ignore alert if reloading page

I am detecting the end of a webrtc stream in JavaScript like this...
stream.getVideoTracks()[0].onended = () => {
alert('Feed Has Ended');
};
This is working correctly, but if the user refreshes or reloads the page then the alert is also shown.
I understand that this is technically correct, but how can I get it to not display the alert under those conditions?

Why don't you use a global boolean to check if video is playing or not? When you will reload or refresh the page, isVideoRunning will become false and alert won't show.
Like
this.isVideoRunning = false;
On addtrack,
this.rtcPeerCon_.ontrack = function (event) {
if (!this.rtcPeerCon_) {
return;
}
if( !this.remoteVideo_ ) {
return;
}
this.remoteVideo_.srcObject = event.streams[0];
this.isVideoRunning = true;
}
then in your onStream ended callback you can check
if (this.isVideoRunning) {
alert('whatever');
this.isVideoRunning = false;
}
(I wanted this to be comment but I am not allowed to comment yet)

How to use setInterval to have Refresh on by default but off with a switch

I would like to use setInterval to control a refresh of my page. I would like to have it running by default (on when the page loads) but I need to be able to turn it off at certain times. So I've written what you see below. The problem is that the refresh is not on when the page first displays. It only comes on after I click the button twice to re-activate the update the setInterval controls.
My html button definition looks like this;
<button id="autoref" type="button" name="autoref" onclick="stopAutoRef();">Stop Auto Ref</button>
My stopAutoRef function looks like this;
function stopAutoRef() {
if ($("#autoref").text() == "Stop Auto Ref") {
$("#autoref").html('Start Auto Ref'); // You see this if Refresh is not automatically happening
clearInterval();
}else {$("#autoref").html('Stop Auto Ref'); // You see this if Refresh is automatically happening
setInterval(function() {showActivities(document.getElementById("select1").value);}, 60000);
}
}

setInterval returns an ID which must be passed to clearInterval to stop it. You'd also want to call your function, startAutoRef(), immediately in addition to on click to initiate the default behavior of refreshing.
var autoRefId = null;
function stopAutoRef() {
if (autoRefId !== null) {
$("#autoref").html('Start Auto Ref'); // You see this if Refresh is not automatically happening
clearInterval(autoRefId);
autoRefId = null;
} else {
$("#autoref").html('Stop Auto Ref'); // You see this if Refresh is automatically happening
autoRefId = setInterval(function() {showActivities(document.getElementById("select1").value);}, 60000);
}
}
stopAutoRef();

clearinterval generally requires a argument of which function to stop. so try this maybe?
try this:
HTML:
<button id = 'b' onclick = 'stop(this)' value = 'true'>Stop ref</button>
Javascript:
var myfunc = setInterval(function(){
location.reload();
},1000);;
function stop(button){
if(button.innerHTML == 'Stop ref'){
button.innerHTML = 'Start ref';
clearInterval(myfunc);
}
else{
button.innerHTML = 'Stop ref';
myfunc = setInterval(function(){
location.reload();
},1000);;
}
}

Prevent calling ajax on scroll when already called

I have a plugin that tells me if an element is visible in the viewport with $('#element').visible() (set to true when visible).
Now I want to create a function that I scroll down a page and load new content with ajax. I have this so far:
window.onscroll = function() {
console.log($('#ele').visible());
if ($('#ele').visible()) {
//ajax call comes here
}
};
As soon as I see the element my log shows true:
I don't have problems implementing the ajax-request now, but shouldn't I block this function to occur only once? How could I prevent that a new element that already has been loaded to load again (prevent using ajax again)?
I thought of using a boolean-variable, but my problem is that I don't know how to implement that because if I set a variable, how would the browser know it's value? Because on every move of my mousewheel it cant remember what that variable's value was?
EDIT:
I tried the code of Ismail and it never reaches the ajax call (alert won't show).
window.onscroll = function() {
var ajaxExecuted = false;
var ele = $('#load_more').visible();
console.log(ele);
return function() {
if (ajaxExecuted) return;
if (ele) {
alert("OK");
var ajaxArray;
ajaxArray = { page: 2 }
ajaxLoadContent(ajaxArray, "load_more", "ajax_load");
ajaxExecuted = true;
}
}
};

You can use this:
window.onscroll = (function() {
var ajaxExecuted = false;
return function() {
if(ajaxExecuted) return;
if ($('#ele').visible()) {
$.ajax({...}).success(function() {
//Your code here;
ajaxExecuted = true;
});
}
}
})();

One easy solution: set a boolean to true when the element first becomes visible and set it to false when it stops being visible. Only fire the request if those states mismatch (i.e. if it's visible but the boolean is false - that means it's the first time you've seen the window. You'd then set the bool afterwards so it won't fire off anymore until it disappears and reappears again).

How to close html dialog in Android on press of back key

I have created a webview in Android in which i am loading my html file.At the time of clicking a button i am displaying a pop up like alert dialog which is developed in html itself.
Now problem is as soon as i press back button on android phone,application is returning to previous page.But with identical behavior only dialog should be closed and application should be on same page.
How can i achieve it?
Thanks

I think you do not need the JavascriptInterface (as #Henil posted). I would do it like so:
in Java - onBackPressed:
if (webView.getUrl.equals("yourPopupUrl.com")) {
webView.loadUrl("javascript:goAwayPopup();");
return;
}
in JS:
function goAwayPopup() {
var popUp = document.getElementById("popUp"); // in my case popUp is just a <div>
var isVisible = popUp .offsetWidth > 0 || popUp .offsetHeight > 0;
if (isVisible) {
popUp.style.display = 'none';
}
}
EDIT:
Solution with JavascriptInterface:
in JS - function which is called when dialog popups:
function popUp() {
if (typeof Android != "undefined"){
if (Android.popUp!= "undefined") {
Android.popUp();
}
}
}
in Java:
define a inner class and a boolean field in your Activity
declare the bridge to your webview
override onBackPressed
private boolean isPopUpVisible = false;
// some code...
webView.addJavascriptInterface(new MyJavascriptBridge(), "Android");
// some code...
class MyJavascriptBridge {
public void popUp() {
if (isPopUpVisible)
isPopUpVisible = false;
else
isPopUpVisible = true;
}
}
onBackPressed:
if (isPopUpVisible) {
webView.loadUrl("javascript:goAwayPopup();");
return;
}
JS, again:
function goAwayPopup() {
// close alert here...
popUp(); // sets isPopUpVisible to false
}
Here is a post of closing a alert: How to "auto close" Alert boxes

Use java script interface and handle html page from that interface

How to check Popup blocker enabled Without loading popup window in chrome using Javascript [duplicate]

I am aware of javascript techniques to detect whether a popup is blocked in other browsers (as described in the answer to this question). Here's the basic test:
var newWin = window.open(url);
if(!newWin || newWin.closed || typeof newWin.closed=='undefined')
{
//POPUP BLOCKED
}
But this does not work in Chrome. The "POPUP BLOCKED" section is never reached when the popup is blocked.
Of course, the test is working to an extent since Chrome doesn't actually block the popup, but opens it in a tiny minimized window at the lower right corner which lists "blocked" popups.
What I would like to do is be able to tell if the popup was blocked by Chrome's popup blocker. I try to avoid browser sniffing in favor of feature detection. Is there a way to do this without browser sniffing?
Edit: I have now tried making use of newWin.outerHeight, newWin.left, and other similar properties to accomplish this. Google Chrome returns all position and height values as 0 when the popup is blocked.
Unfortunately, it also returns the same values even if the popup is actually opened for an unknown amount of time. After some magical period (a couple of seconds in my testing), the location and size information is returned as the correct values. In other words, I'm still no closer to figuring this out. Any help would be appreciated.

Well the "magical time" you speak of is probably when the popup's DOM has been loaded. Or else it might be when everything (images, outboard CSS, etc.) has been loaded. You could test this easily by adding a very large graphic to the popup (clear your cache first!). If you were using a Javascript Framework like jQuery (or something similar), you could use the ready() event (or something similar) to wait for the DOM to load before checking the window offset. The danger in this is that Safari detection works in a conflicting way: the popup's DOM will never be ready() in Safari because it'll give you a valid handle for the window you're trying to open -- whether it actually opens or not. (in fact, i believe your popup test code above won't work for safari.)
I think the best thing you can do is wrap your test in a setTimeout() and give the popup 3-5 seconds to complete loading before running the test. It's not perfect, but it should work at least 95% of the time.
Here's the code I use for cross-browser detection, without the Chrome part.
function _hasPopupBlocker(poppedWindow) {
var result = false;
try {
if (typeof poppedWindow == 'undefined') {
// Safari with popup blocker... leaves the popup window handle undefined
result = true;
}
else if (poppedWindow && poppedWindow.closed) {
// This happens if the user opens and closes the client window...
// Confusing because the handle is still available, but it's in a "closed" state.
// We're not saying that the window is not being blocked, we're just saying
// that the window has been closed before the test could be run.
result = false;
}
else if (poppedWindow && poppedWindow.test) {
// This is the actual test. The client window should be fine.
result = false;
}
else {
// Else we'll assume the window is not OK
result = true;
}
} catch (err) {
//if (console) {
// console.warn("Could not access popup window", err);
//}
}
return result;
}
What I do is run this test from the parent and wrap it in a setTimeout(), giving the child window 3-5 seconds to load. In the child window, you need to add a test function:
function test() {}
The popup blocker detector tests to see whether the "test" function exists as a member of the child window.
ADDED JUNE 15 2015:
I think the modern way to handle this would be to use window.postMessage() to have the child notify the parent that the window has been loaded. The approach is similar (child tells parent it's loaded), but the means of communication has improved. I was able to do this cross-domain from the child:
$(window).load(function() {
this.opener.postMessage({'loaded': true}, "*");
this.close();
});
The parent listens for this message using:
$(window).on('message', function(event) {
alert(event.originalEvent.data.loaded)
});
Hope this helps.

Just one improvement to InvisibleBacon's snipet (tested in IE9, Safari 5, Chrome 9 and FF 3.6):
var myPopup = window.open("popupcheck.htm", "", "directories=no,height=150,width=150,menubar=no,resizable=no,scrollbars=no,status=no,titlebar=no,top=0,location=no");
if (!myPopup)
alert("failed for most browsers");
else {
myPopup.onload = function() {
setTimeout(function() {
if (myPopup.screenX === 0) {
alert("failed for chrome");
} else {
// close the test window if popups are allowed.
myPopup.close();
}
}, 0);
};
}

The following is a jQuery solution to popup blocker checking. It has been tested in FF (v11), Safari (v6), Chrome (v23.0.127.95) & IE (v7 & v9). Update the _displayError function to handle the error message as you see fit.
var popupBlockerChecker = {
check: function(popup_window){
var _scope = this;
if (popup_window) {
if(/chrome/.test(navigator.userAgent.toLowerCase())){
setTimeout(function () {
_scope._is_popup_blocked(_scope, popup_window);
},200);
}else{
popup_window.onload = function () {
_scope._is_popup_blocked(_scope, popup_window);
};
}
}else{
_scope._displayError();
}
},
_is_popup_blocked: function(scope, popup_window){
if ((popup_window.innerHeight > 0)==false){ scope._displayError(); }
},
_displayError: function(){
alert("Popup Blocker is enabled! Please add this site to your exception list.");
}
};
Usage:
var popup = window.open("http://www.google.ca", '_blank');
popupBlockerChecker.check(popup);
Hope this helps! :)

Rich's answer isn't going to work anymore for Chrome. Looks like Chrome actually executes any Javascript in the popup window now. I ended up checking for a screenX value of 0 to check for blocked popups. I also think I found a way to guarantee that this property is final before checking. This only works for popups on your domain, but you can add an onload handler like this:
var myPopup = window.open("site-on-my-domain", "screenX=100");
if (!myPopup)
alert("failed for most browsers");
else {
myPopup.onload = function() {
setTimeout(function() {
if (myPopup.screenX === 0)
alert("failed for chrome");
}, 0);
};
}
As many have reported, the "screenX" property sometimes reports non-zero for failed popups, even after onload. I experienced this behavior as well, but if you add the check after a zero ms timeout, the screenX property always seems to output a consistent value.
Let me know if there are ways to make this script more robust. Seems to work for my purposes though.

This worked for me:
cope.PopupTest.params = 'height=1,width=1,left=-100,top=-100,location=no,toolbar=no,menubar=no,scrollbars=no,resizable=no,directories=no,status=no';
cope.PopupTest.testWindow = window.open("popupTest.htm", "popupTest", cope.PopupTest.params);
if( !cope.PopupTest.testWindow
|| cope.PopupTest.testWindow.closed
|| (typeof cope.PopupTest.testWindow.closed=='undefined')
|| cope.PopupTest.testWindow.outerHeight == 0
|| cope.PopupTest.testWindow.outerWidth == 0
) {
// pop-ups ARE blocked
document.location.href = 'popupsBlocked.htm';
}
else {
// pop-ups are NOT blocked
cope.PopupTest.testWindow.close();
}
The outerHeight and outerWidth are for chrome because the 'about:blank' trick from above doesn't work in chrome anymore.

I'm going to just copy/paste the answer provided here: https://stackoverflow.com/a/27725432/892099 by DanielB . works on chrome 40 and it's very clean. no dirty hacks or waiting involves.
function popup(urlToOpen) {
var popup_window=window.open(urlToOpen,"myWindow","toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=yes, resizable=yes, copyhistory=yes, width=400, height=400");
try {
popup_window.focus();
}
catch (e) {
alert("Pop-up Blocker is enabled! Please add this site to your exception list.");
}
}

How about a Promise approach ?
const openPopUp = (...args) => new Promise(s => {
const win = window.open(...args)
if (!win || win.closed) return s()
setTimeout(() => (win.innerHeight > 0 && !win.closed) ? s(win) : s(), 200)
})
And you can use it like the classic window.open
const win = await openPopUp('popuptest.htm', 'popuptest')
if (!win) {
// popup closed or blocked, handle alternative case
}
You could change the code so that it fail the promise instead of returning undefined, I just thought that if was an easier control flow than try / catch for this case.

Check the position of the window relative to the parent. Chrome makes the window appear almost off-screen.

I had a similar problem with popups not opening in Chrome. I was frustrated because I wasn't trying to do something sneaky, like an onload popup, just opening a window when the user clicked. I was DOUBLY frustrated because running my function which included the window.open() from the firebug command line worked, while actually clicking on my link didn't! Here was my solution:
Wrong way: running window.open() from an event listener (in my case, dojo.connect to the onclick event method of a DOM node).
dojo.connect(myNode, "onclick", function() {
window.open();
}
Right way: assigning a function to the onclick property of the node that called window.open().
myNode.onclick = function() {
window.open();
}
And, of course, I can still do event listeners for that same onclick event if I need to. With this change, I could open my windows even though Chrome was set to "Do not allow any site to show pop-ups". Joy.
If anyone wise in the ways of Chrome can tell the rest of us why it makes a difference, I'd love to hear it, although I suspect it's just an attempt to shut the door on malicious programmatic popups.

Here's a version that is currently working in Chrome. Just a small alteration away from Rich's solution, though I added in a wrapper that handles the timing too.
function checkPopupBlocked(poppedWindow) {
setTimeout(function(){doCheckPopupBlocked(poppedWindow);}, 5000);
}
function doCheckPopupBlocked(poppedWindow) {
var result = false;
try {
if (typeof poppedWindow == 'undefined') {
// Safari with popup blocker... leaves the popup window handle undefined
result = true;
}
else if (poppedWindow && poppedWindow.closed) {
// This happens if the user opens and closes the client window...
// Confusing because the handle is still available, but it's in a "closed" state.
// We're not saying that the window is not being blocked, we're just saying
// that the window has been closed before the test could be run.
result = false;
}
else if (poppedWindow && poppedWindow.outerWidth == 0) {
// This is usually Chrome's doing. The outerWidth (and most other size/location info)
// will be left at 0, EVEN THOUGH the contents of the popup will exist (including the
// test function we check for next). The outerWidth starts as 0, so a sufficient delay
// after attempting to pop is needed.
result = true;
}
else if (poppedWindow && poppedWindow.test) {
// This is the actual test. The client window should be fine.
result = false;
}
else {
// Else we'll assume the window is not OK
result = true;
}
} catch (err) {
//if (console) {
// console.warn("Could not access popup window", err);
//}
}
if(result)
alert("The popup was blocked. You must allow popups to use this site.");
}
To use it just do this:
var popup=window.open('location',etc...);
checkPopupBlocked(popup);
If the popup get's blocked, the alert message will display after the 5 second grace period (you can adjust that, but 5 seconds should be quite safe).

This fragment incorporates all of the above - For some reason - StackOverflow is excluding the first and last lines of code in the code block below, so I wrote a blog on it. For a full explanation and the rest of the (downloadable) code have a look at
my blog at thecodeabode.blogspot.com
var PopupWarning = {
init : function()
{
if(this.popups_are_disabled() == true)
{
this.redirect_to_instruction_page();
}
},
redirect_to_instruction_page : function()
{
document.location.href = "http://thecodeabode.blogspot.com";
},
popups_are_disabled : function()
{
var popup = window.open("http://localhost/popup_with_chrome_js.html", "popup_tester", "width=1,height=1,left=0,top=0");
if(!popup || popup.closed || typeof popup == 'undefined' || typeof popup.closed=='undefined')
{
return true;
}
window.focus();
popup.blur();
//
// Chrome popup detection requires that the popup validates itself - so we need to give
// the popup time to load, then call js on the popup itself
//
if(navigator && (navigator.userAgent.toLowerCase()).indexOf("chrome") > -1)
{
var on_load_test = function(){PopupWarning.test_chrome_popups(popup);};
var timer = setTimeout(on_load_test, 60);
return;
}
popup.close();
return false;
},
test_chrome_popups : function(popup)
{
if(popup && popup.chrome_popups_permitted && popup.chrome_popups_permitted() == true)
{
popup.close();
return true;
}
//
// If the popup js fails - popups are blocked
//
this.redirect_to_instruction_page();
}
};
PopupWarning.init();

Wow there sure are a lot of solutions here. This is mine, it uses solutions taken from the current accepted answer (which doesn't work in latest Chrome and requires wrapping it in a timeout), as well as a related solution on this thread (which is actually vanilla JS, not jQuery).
Mine uses a callback architecture which will be sent true when the popup is blocked and false otherwise.
window.isPopupBlocked = function(popup_window, cb)
{
var CHROME_CHECK_TIME = 2000; // the only way to detect this in Chrome is to wait a bit and see if the window is present
function _is_popup_blocked(popup)
{
return !popup.innerHeight;
}
if (popup_window) {
if (popup_window.closed) {
// opened OK but was closed before we checked
cb(false);
return;
}
if (/chrome/.test(navigator.userAgent.toLowerCase())) {
// wait a bit before testing the popup in chrome
setTimeout(function() {
cb(_is_popup_blocked(popup_window));
}, CHROME_CHECK_TIME);
} else {
// for other browsers, add an onload event and check after that
popup_window.onload = function() {
cb(_is_popup_blocked(popup_window));
};
}
} else {
cb(true);
}
};

Jason's answer is the only method I can think of too, but relying on position like that is a little bit dodgy!
These days, you don't really need to ask the question “was my unsolicited popup blocked?”, because the answer is invariably “yes” — all the major browsers have the popup blocker turned on by default. Best approach is only ever to window.open() in response to a direct click, which is almost always allowed.

HI
I modified the solutions described above slightly and think that it is working for Chrome at least.
My solution is made to detect if popup is blocked when the main page is opened, not when popup is opened, but i am sure there are some people that can modify it.:-)
The drawback here is that the popup-window is displayed for a couple of seconds (might be possible to shorten a bit) when there is no popup-blocker.
I put this in the section of my 'main' window
<script type="text/JavaScript" language="JavaScript">
var mine = window.open('popuptest.htm','popuptest','width=1px,height=1px,left=0,top=0,scrollbars=no');
if(!mine|| mine.closed || typeof mine.closed=='undefined')
{
popUpsBlocked = true
alert('Popup blocker detected ');
if(mine)
mine.close();
}
else
{
popUpsBlocked = false
var cookieCheckTimer = null;
cookieCheckTimer = setTimeout('testPopup();', 3500);
}
function testPopup()
{
if(mine)
{
if(mine.test())
{
popUpsBlocked = false;
}
else
{
alert('Popup blocker detected ');
popUpsBlocked = true;
}
mine.close();
}
}
</script>
The popuptest looks like this:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Popup test</title>
<script type="text/javascript" language="Javascript">
function test() {if(window.innerHeight!=0){return true;} else return false;}
</script>
</head>
<body>
</body>
</html>
As i call the test-function on the popup-page after 3500 ms the innerheight has been set correctly by Chrome.
I use the variable popUpsBlocked to know if the popups are displayed or not in other javascripts.
i.e
function ShowConfirmationMessage()
{
if(popUpsBlocked)
{
alert('Popups are blocked, can not display confirmation popup. A mail will be sent with the confirmation.');
}
else
{
displayConfirmationPopup();
}
mailConfirmation();
}

function openPopUpWindow(format)
{
var win = window.open('popupShow.html',
'ReportViewer',
'width=920px,height=720px,left=50px,top=20px,location=no,directories=no,status=no,menubar=no,toolbar=no,resizable=1,maximize:yes,scrollbars=0');
if (win == null || typeof(win) == "undefined" || (win == null && win.outerWidth == 0) || (win != null && win.outerHeight == 0) || win.test == "undefined")
{
alert("The popup was blocked. You must allow popups to use this site.");
}
else if (win)
{
win.onload = function()
{
if (win.screenX === 0) {
alert("The popup was blocked. You must allow popups to use this site.");
win.close();
}
};
}
}

As far as I can tell (from what I've tested) Chrome returns a window object with location of 'about:blank'.
So, the following should work for all browsers:
var newWin = window.open(url);
if(!newWin || newWin.closed || typeof newWin.closed=='undefined' || newWin.location=='about:blank')
{
//POPUP BLOCKED
}