Develop Reference

java script code for preventing user from closing browser without alert messege in chrome

This code is giving alert message but I want to prevent user from closing browser. If I comment this line and place alert code before below given code it works, but I want not to show any dialog box.
set Interval(function () {alert("**Hello")}, 10);
I tried above code but I close browser from current tab also:
{
window.onbeforeunload = confirmExit;
function confirmExit() {
return "You have attempted to leave this page. Are you sure?";
}
confirmExit();
}

Try this Code..
window.onbeforeunload = function (e) {
e = e || window.event;
// For IE and Firefox prior to version 4
if (e) {
e.returnValue = 'Any string';
}
// For Safari
return 'Any string';
};
Here is the Fiddle try this also.....

JavaScript, Print Screen and copy and paste

I got some code from the internet, below, and used it in a mock exam application I am doing. This is suppose to prevent people from Printing Screen, copying or cutting from the exam page. The code works perfectly well in Internet Explorer but does not work in the other browsers. I need help to make the code below work in the other browsers to avoid cheating at the site during mock exam. Below is the code:
<script type="text/javascript">
function AccessClipboardData() {
try {
window.clipboardData.setData('text', "No print data");
} catch (err) {
txt = "There was an error on this page.\n\n";
txt += "Error description: " + err.description + "\n\n";
txt += "Click OK to continue.\n\n";
alert(txt);
}
}
setInterval("AccessClipboardData()", 300);
document.onkeydown = function (ev) {
var a;
ev = window.event;
if (typeof ev == "undefined") {
alert("PLEASE DON'T USE KEYBORD");
}
a = ev.keyCode;
alert("PLEASE DON'T USE KEYBORD");
return false;
}
document.onkeyup = function (ev) {
var charCode;
if (typeof ev == "undefined") {
ev = window.event;
alert("PLEASE DON'T USE KEYBORD");
} else {
alert("PLEASE DON'T USE KEYBORD");
}
return false;
}

Please know that it is entirely impossible to prevent users from copying or screencapping your site from javascript, seeing how they could simply disable js or your function in particular as has been mentioned in the comments already.
If you simply want to discourage people as much as possible you can still use your code, however window.clipboardData.setData only works in IE so it is not strange you would get an error message in other browsers, for thos you would have to use execCommand to copy a set message to the clipboard at you set interval
documnet.execCommand(delete, false, null)
to delete the current selection and then
documnet.execCommand(copy, false, null)
to copy the currently selected text(which you just made sure was nothing)
(for more info on execCommand https://developer.mozilla.org/en-US/docs/Web/API/Document/execCommand)
this should work in Firefox, Safari and Chrome, I know of no way to do this in Opera, as neither command will work in that browser
Note however that this will keep overwritting your clipboard as long as the site is open in the browser, so even if someone tried to copy something else entirely they would be unable.
I would like to point out that I provide this function only to show you what the problem with your code, as you will never be able to do what you want to completely without getting people to install third party rights management software on their computer.

I find the following code at Stackoverflow here, by iDhavalVaja and it worked fine.
<script type="text/javascript">
$(function () {
$(this).bind("contextmenu", function (e) {
e.preventDefault();
});
});
</script>
<script type="text/JavaScript">
function killCopy(e) { return false }
function reEnable() { return true }
document.onselectstart = new Function("return false");
if (window.sidebar) {
document.onmousedown = killCopy;
document.onclick = reEnable;
}
</script>

If you just want to get this working in other browsers, maybe use jQuery (something like this):
$(document).keydown(function (e) {
alert("PLEASE DON'T USE KEYBORD");
});

prevent Page refresh after pop-up

How can i prevent page refresh when the user clicks on the OK button of the javascript alert window.
<asp:Button ID="btnComplete" runat="server" Text="Complete" OnClientClick ="verify_complete()" />
function verify_complete() {
if (!chkCmnts()) {
alert("Categories/comments are required. ");
return false;
}
}
Thanks
BB

You are already returning false from the JS so you need to change your markup to:
<asp:Button ID="btnComplete" runat="server" Text="Complete" OnClientClick ="return verify_complete()" />
If the verify_complete() function returns true it will post back, if it doesn't, it won't.

You can not prevent this, but you can notify the user via a popup that he should not reload. This is done with the onbeforeunload window event, best documented at MDN.
add this to your popup window in a Script-Tag
var controllVar = 1;
add this to your parent window. (popup is the return of window.open(...)). Here is actually some intensive error testing, because IE in it's various flavours shows more than one Bug.
window.onbeforeunload = function (e) {
//here we try accessing the popup
try {
if(!popup && popup.controllVar != 1) {
return;
}
} catch(e) {
return;
}
e = e || window.event;
// For IE and Firefox prior to version 4
if (e) {
e.returnValue = 'YOUR ERROR MESSAGE';
}
// For Safari
return 'YOUR ERROR MESSAGE';
};
This will behave exactly like here on Stackoverflow, if you add some text to the answer textarea and than try to leave the page.

How to determine which control in window.onbeforeunload in javascript caused the event

I have set up in javascript:
var onBeforeUnloadFired = false;
window.onbeforeunload = function (sender, args)
{
if(window.event){
if(!onBeforeUnloadFired) {
onBeforeUnloadFired = true;
window.event.returnValue = 'You will lose any unsaved changes!'; //IE
}
}
else {
return 'You will lose any unsaved changes!'; //FX
}
windows.setTimeout("ResetOnBeforeUnloadFired()", 1000);
}
function ResetOnBeforeUnloadFired() {
//Need this variable to prevent IE firing twice.
onBeforeUnloadFired = false;
}
I'm trying to achieve an edit screen where the user is warned before navigating away. It works fine except I get the pop up for normal post backs of button clicks. I'm hoping to avoid this so I'm figuring if I could determine which button was pressed it would work.
Does anybody know how to determine which button was pressed in the windows.onbeforeunload?
Alternatively anyone know a better approach to what I'm trying to achieve?

Solved this by putting into an update panel all edit items TextBoxes etc.
Now the windows.onbeforeunload only fires for components external to this.

Another method, if you can't "control" that deep you controls, is to mark somewhat the "good controls", that is the ones which should not trigger the away-navigation logic.
That is easily achievable setting a global javascript variable such as
var isGoodLink=false;
window.onbeforeunload = function (e) {
var message = "Whatever";
e = e || window.event;
if (!isGoodLink) {
// For IE and Firefox
if (e) {
e.returnValue = message;
}
// For Safari
return message;
}
};
function setGoodLink() {
isGoodLink=true;
}
And add the setGoodLink function on the events you want to keep safe:
<button type="button" onclick="javascript:setGoodLink() ">I am a good button!</button>

onbeforeunload confirmation screen customization

Is it possible to create a custom confirmation box for the onbeforeunload event in a browser? I tried but then I get 2 confirmation boxes (one from me which is nothing more than return confirm... and then the standard one from the browser).
At the moment my code looks like:
var inputChanged = false;
$(window).load(function() {
window.onbeforeunload = navigateAway;
$(':input').bind('change', function() { inputChanged = true; });
});
function navigateAway(){
if(inputChanged){
return 'Are you sure you want to navigate away?';
}
}
I'm using jQuery for this.

window.onbeforeunload = function (e) {
var message = "Your confirmation message goes here.",
e = e || window.event;
// For IE and Firefox
if (e) {
e.returnValue = message;
}
// For Safari
return message;
};
Please note: Most browsers put this message after some other text. You do not have complete control of the content of the confirmation dialog.

No, you can't avoid the standard one from the browser. All you can do is inject some custom text into it; if you use the following event handler (registered the prototype lib way):
Event.observe(window, "beforeunload", function(event) {
if (showMyBeforeUnloadConfirmation)
event.returnValue = "foo bar baz";
});
(and showMyBeforeUnloadConfirmation is true) you'll get the browser's standard confirmation with the following text:
Are you sure you want to navigate away from this page?
foo bar baz
Press OK to continue, or Cancel to stay on the current page.
[ OK ] [ Cancel ]

I faced the same problem, I was able to get its own dialog box with my message, but the problems I faced were:
It was giving message on all navigations and I wanted it only for close click.
With my own confirmation message if user selects "Cancel", it still shows the browser's default dialog box.
Following is the solutions code I found, which I wrote on my Master page.
function closeMe(evt) {
if (typeof evt == 'undefined') {
evt = window.event;
}
if (evt && evt.clientX >= (window.event.screenX - 150) && evt.clientY >= -150 && evt.clientY <= 0) {
return "Do you want to log out of your current session?";
}
}
window.onbeforeunload = closeMe;