I have a problem with JavaScript and Opera.
I want to fire an JavaScript function onLoad but opera
ignores it when I reload the page or use the back button to come back.
My code looks like this:
HTML
...
<body onload = "doSomething()">
...
//Javascript
if (window.opera)
{
opera.setOverrideHistoryNavigationMode('compatible');
history.navigationMode = 'compatible';
}
...
function doSomething(){
alert("HI");
}
The first time I load the page I get an Alert but if
I reload the page or use the back button to come back I
don't get an alert.
Does anyone know how to fix this problem?
Chrome, Firefox and even IE work fine.
Related
I have this simple code
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<!--<script src="angular.min.js"></script>-->
<script>
window.onload = function () {
window.addEventListener("unload", function () {
debugger;
});
window.addEventListener("beforeunload", function () {
debugger;
});
window.onbeforeunload = function () {
}
}
</script>
</head>
<body ng-app="app">
</body>
</html>
I want unload or beforeunload events be fired after I refresh the page. This is not happening in Chrome Versión 67.0.3396.62. I have tried firefox and edge and it works well. It also works when i close the tab. The error ocurrs only when i refresh the page.
You've run into an issue that was already reported. It looks like a bug, but according to a Chrome dev (kozy) it is a feature:
Thanks for repro. It is actually feature. As soon as you pressed reload we ignore all breakpoints before page reloaded. It is useful all the time when you have a lot of breakpoints and need to reload page to restart debugging session.
Workaround: instead of pressing reload button you can navigate to the same url using omnibox then all breakpoint will work as expected.
I've added bold emphasis to point out the workaround proposed by kozy. I've tried it and found that it works.
Other than the issue with the debugger statement, the handlers are executed whether you are reloading or closing the tab. In both cases that follow, I get the stock prompt that Chrome provides when returning true:
window.addEventListener("beforeunload", function (ev) {
ev.returnValue = true; // `return true` won't work here.
});
This works too:
window.onbeforeunload = function () {
return true;
}
It used to be that you could use a return value with a message and the browser would show your custom message but browsers generally no longer support this.
Whether or not you want to set the handler for beforeunload inside a handler for load is entirely dependent on your goals. For instance, I have an application for editing documents that does not set the beforeunload handler until the application has started initializing, which is much later than the load event. The beforeunload handler is there to make sure the user does not leave the page with unsaved modifications.
I am trying to send data to a popup window which opens by clicking a button.
All my code is in php where I include javascript and html, I will just show html and js here.
Consider my popup window (say, popupwindow.html) code as just
<div id = 'getData'></div>
Now on the page(say, main.js) where I put the button clicking which the popup opens, I am computing some data and trying to send it to popupwindow.html.
Here is relevant main.js code that gets executed after clicking the button
var popup = window.open("popupwindow.html", "popup", extraParams); //ignore extraParams
$(popup).on('load', function() {
//console.log("inside onload function");
popup.document.getElementById("getData").innerHTML = data; //here data is some string
});
Now this code works perfectly on Chrome and Firefox, but in IE load() function does not get executed. I know this because the console.log line when uncommented, does not print on the console. Tried versions of jQuery from 1.2.3 to 2.2.1 where the code runs successfully on Chrome and Firefox(but not in IE)
Note: I cannot execute the required code on popup page(popupwindow.html) because of some constraints. I have to write it on main.js and send it to popup.
I saw all other questions which said onload() or similar function in IE gives problems but I still could not find the appropriate solution. Please let me know how I can fix this for IE.
I am having an issue with print on Safari. My System is Windows 7, and this function works fine in all other browsers except Safari. Here is the situation:
window.onload = function(){
console.log('before print');
window.print();
}
It won't output the log in console panel, but the print page will appear first, after i choose cancel in print page, the log will be output.
Does any body came up with this issue? Any help will be appreciated.
Updated
Here is the situation i have:
We need to print a page whose content can be changed by user by checking and unchecking check box, and only the content part of this page should be printed, so we create a new page that only contains the content for printing. In this page, we need to hide the unnecessary content that is not selected by user, so we need to do some DOM operation before window.print() get called. The console.log() is just an example code for observing. I tried to add an <div id='test'>Test HTML</div> in test HTML and add
var test = document.getElementById('test');
test.style.background = 'yellow';
before window.print();, it shows the same result in my Safari browser, the 'Test HTML' will not turn to yellow until i click cancel button in print panel, so it's not just the console.log issue.
Updated
I am using Safari 5.1.7(7534.57.2) on Windows 7
For me, the setTimeout solution didn't work. I found this jQuery plugin https://github.com/jasonday/printThis that has plenty of workarounds for window.print() because it seems not to be fully supported by all browsers.
I took this line that worked for me Safari document.execCommand("print", false, null)
and this worked ok for me for now in safari and chrome
try {
document.execCommand('print', false, null);
}
catch(e) {
window.print();
}
This is odd behavior. I tested in Safari 6.1 on Mac.
But may I ask why you need to log something before the printing? Because it seems that all the functions are being executed before the printing panel pops up:
<script src="http://code.jquery.com/jquery-2.1.0.min.js"></script>
<script>
window.onload = function() {
$('body').html('before print');
console.log('before print');
window.print();
};
</script>
When you look at the print preview, the page will have the text "before print" on it. For some reason, the console will log the text only when the print panel closes, but in my opinion that doesn't really matter for your visitors. You can manipulate DOM and change the page before the printing process as you like.
After several times trying, below code works, but i don't know the reason, can anybody explain? Or this is a Safari Bug?
window.onload = function() {
$('body').html('After change');
setTimeout(window.print, 1000);
};
Safari prints the page before it is loaded unlike other browsers. Hence window.onload() can be used in the code of the newly opened html page. But if the page opened is non html content, then it is not possible. The below solution is global across browsers and type of content open.
var printWindow = window.open(url, '_blank');
$(printWindow).load(function()
{
this.print();
});
Adding one more solution which worked for my case:
First make your popup window.
$( ".myButton" ).click(function() {
var url = 'www.google.com';
var printWindow = window.open( url, '_blank');
printWindow.focus();
});
Then, inside the HTML page which is loaded in the popup:
$(window).bind("load", function() {
setTimeout( function () {
try {
document.execCommand('print', false, null);
}
catch(e) {
window.print();
}
}, 500);
});
I am aware that until recently onafterprint was only native to IE. Recently HTML5 has added it to its list of events. I have only been successful in using it in Firefox but cannot get it to function in Chrome or Safari.
It appears to only function in Firefox when its used in the body:
<body onafterprint="printIt()">
The script for the function is this:
$(document).ready(function() {
$('.printMe').click(function() {
window.print();
return false;
});
});
function printIt()
{
$('#confirmPrint').show();
};
By clicking the .printMe button, it opens the print window. Clicking print or cancel will show a message in #confirmPrint. I'm not so worried about being able to tell whether they are clicking cancel or print. I am only concerned with it functioning in Chrome and Safari. Any help is much appreciated. I am using jQuery as well, if that is not already obvious.
After some experiments, I think I can safely say that onafterprint is not worth considering.
Firefox fires it even if the user clicked Cancel instead of OK in the print dialog
IE8 apparently fires it even before the print dialog appears
Chrome doesn't fire it at all
Instead, just do whatever you wanted to do directly after calling print(), i.e.
$(document).ready(function() {
$('.printMe').click(function() {
window.print();
printIt();
return false;
});
});
function printIt()
{
$('#confirmPrint').show();
};
When I use the back button on Firefox to reach a previously visited page, scripts on that page won't run again.
Is there any fix/workaround to have the scripts execute again when viewing the page the second time?
Please note that I have tested the same pages on Google Chrome and Internet Explorer and they work as intended.
Here are the files and the steps I used to test the problem:
(navigate to 0.html, click to get to 1.html, back button)
0.html
<html><body>
<script>
window.onload = function() { alert('window.onload alert'); };
alert('inline alert');
</script>
Click Me!
</body></html>
1.html
<html><body>
<p>Go BACK!</p>
</body></html>
Set an empty function to be called on window.onunload:
window.onunload = function(){};
e.g.
<html><body>
<script type="text/javascript">
window.onload = function() { alert('window.onload alert'); };
window.onunload = function(){};
alert('inline alert');
</script>
Click Me!
</body></html>
Source:
http://www.firefoxanswer.com/firefox/672-firefoxanswer.html (Archived Version)
When I use the back button on Firefox to reach a previously visited page, scripts on that page won't run again.
That's correct and that's a good thing.
When you hit a link in Firefox (and Safari, and Opera), it does not immediately destroy your page to go onto the next one. It keeps the page intact, merely hiding it from view. Should you hit the back button, it will then bring the old page back into view, without having to load the document again; this is much faster, resulting in smoother back/forward page transitions for the user.
This feature is called the bfcache.
Any content you added to the page during the user's previous load and use of it will still be there. Any event handlers you attached to page elements will still be attached. Any timeouts/intervals you set will still be active. So there's rarely any reason you need to know that you have been hidden and re-shown. It would be wrong to call onload or inline script code again, because any binding and content generation you did in that function would be executing a second time over the same content, with potentially disastrous results. (eg. document.write in inline script would totally destroy the page.)
The reason writing to window.onunload has an effect is that the browsers that implement bfcache have decided that — for compatibility with pages that really do need to know when they're being discarded — any page that declares an interest in knowing when onunload occurs will cause the bfcache to be disabled. That page will be loaded fresh when you go back to it, instead of fetched from the bfcache.
So if you set window.onunload= function() {};, what you're actually doing is deliberately breaking the bfcache. This will result in your pages being slow to navigate, and should not be used except as a last resort.
If you do need to know when the user leaves or comes back to your page, without messing up the bfcache, you can trap the onpageshow and onpagehide events instead:
window.onload=window.onpageshow= function() {
alert('Hello!');
};
You can check the persisted property of the pageshow event. It is set to false on initial page load. When page is loaded from cache it is set to true.
window.onpageshow = function(event) {
if (event.persisted) {
alert("From bfcache");
}
};
For some reason jQuery does not have this property in the event. You can find it from original event though.
$(window).bind("pageshow", function(event) {
if (event.originalEvent.persisted) {
alert("From bfcache");
}
});
In my case window.onunload with an empty function didn't help (I tried to set a value for dropdown when user uses backwards button). And window.onload didn't work for other reason - it was overridden by <body onload="...">.
So I tried this using jQuery and it worked like a charm:
$(window).on('pageshow', function() { alert("I'm happy"); });
Wire in an "onunload" event that does nothing:
<html><body>
<script type="text/javascript">
window.onload = function() { alert('window.onload alert'); };
window.onunload = function(){};
alert('inline alert');
</script>
Click Me!
</body></html>
As far as i know Firefox does not fire onLoad event on back.
It should trigger onFocus instead based from this link here.
A simple way to cause a page to execute JavaScript when the user navigates back to it using browser history is the OnPopState event. We use this to pause and replay the video on our home page (https://fynydd.com).
window.onpopstate = function() {
// Do stuff here...
};
for some cases like ajax operations url change listener can be used
$(window).on('hashchange', function() {
....
});