I am doing an online quiz application in PHP. I want to restrict the user from going back in an exam.
I have tried the following script, but it stops my timer.
What should I do?
The timer is stored in file cdtimer.js.
<script type="text/javascript">
window.history.forward();
function noBack()
{
window.history.forward();
}
</script>
<body onLoad="noBack();" onpageshow="if (event.persisted) noBack();" onUnload="">
I have the exam timer which takes a duration for the exam from a MySQL value. The timer starts accordingly, but it stops when I put the code in for disabling the back button. What is my problem?
This question is related to
javascript
browser
This seems to have worked for us in disabling the back button on the browser, as well as the backspace button taking you back.
history.pushState(null, null, $(location).attr('href'));
window.addEventListener('popstate', function () {
history.pushState(null, null, $(location).attr('href'));
});
Just run code snippet right away and try going back
history.pushState(null, null, window.location.href);
history.back();
window.onpopstate = () => history.forward();Very simple and clean function to break the back arrow without interfering with the page afterward.
Benefits:
onbeforeunloadsetInterval, so it doesn't break slow browsers and always works.unbeforeunload which interrupts user with modal dialog.Note: some of the other solutions use onbeforeunload. Please do not use onbeforeunload for this purpose, which pops up a dialog whenever users try to close the window, hit backarrow, etc. Modals like onbeforeunload are usually only appropriate in rare circumstances, such as when they've actually made changes on screen and haven't saved them, not for this purpose.
How It Works
That's it. No further messing around, no background event monitoring, nothing else.
Use It In One Second
To deploy, just add this anywhere on your page or in your JavaScript code:
<script>
/* Break back button */
window.onload = function(){
var i = 0;
var previous_hash = window.location.hash;
var x = setInterval(function(){
i++;
window.location.hash = "/noop/" + i;
if (i==10){
clearInterval(x);
window.location.hash = previous_hash;
}
}, 10);
}
</script>
In my case this was a shopping order. So I disabled the button. When the user clicked back, the button was disabled still. When they clicked back one more time, and then clicked a page button to go forward. I knew their order was submitted and skipped to another page.
In the case when the page actually refreshed which would make the button (theoretically), available; I was then able to react in the page load that the order was already submitted and redirected then too.
It is generally a bad idea overriding the default behavior of the web browser. A client-side script does not have the sufficient privilege to do this for security reasons.
There are a few similar questions asked as well,
You can-not actually disable the browser back button. However, you can do magic using your logic to prevent the user from navigating back which will create an impression like it is disabled. Here is how - check out the following snippet.
(function (global) {
if(typeof (global) === "undefined") {
throw new Error("window is undefined");
}
var _hash = "!";
var noBackPlease = function () {
global.location.href += "#";
// Making sure we have the fruit available for juice (^__^)
global.setTimeout(function () {
global.location.href += "!";
}, 50);
};
global.onhashchange = function () {
if (global.location.hash !== _hash) {
global.location.hash = _hash;
}
};
global.onload = function () {
noBackPlease();
// Disables backspace on page except on input fields and textarea..
document.body.onkeydown = function (e) {
var elm = e.target.nodeName.toLowerCase();
if (e.which === 8 && (elm !== 'input' && elm !== 'textarea')) {
e.preventDefault();
}
// Stopping the event bubbling up the DOM tree...
e.stopPropagation();
};
}
})(window);
This is in pure JavaScript, so it would work in most of the browsers. It would also disable the backspace key, but that key will work normally inside input fields and textarea.
Place this snippet in a separate script and include it on a page where you want this behavior. In the current setup it will execute the onload event of the DOM which is the ideal entry point for this code.
It was tested and verified in the following browsers,
In a modern browser this seems to work:
// https://developer.mozilla.org/en-US/docs/Web/API/History_API
let popHandler = () => {
if (confirm('Go back?')) {
window.history.back()
} else {
window.history.forward()
setTimeout(() => {
window.addEventListener('popstate', popHandler, {once: true})
}, 50) // delay needed since the above is an async operation for some reason
}
}
window.addEventListener('popstate', popHandler, {once: true})
window.history.pushState(null,null,null)
I believe the perfect yet solution is actually pretty straightforward, which I used for many years now.
It's basically assigning the window's "onbeforeunload" event along with the ongoing document 'mouseenter' / 'mouseleave' events so the alert only triggers when clicks are outside the document scope (which then could be either the back or forward button of the browser)
$(document).on('mouseenter', function(e) {
window.onbeforeunload = null;
}
);
$(document).on('mouseleave', function(e) {
window.onbeforeunload = function() { return "You work will be lost."; };
}
);
Try it with ease:
history.pushState(null, null, document.title);
window.addEventListener('popstate', function () {
history.pushState(null, null, document.title);
});
<script>
window.location.hash = "no-back-button";
// Again because Google Chrome doesn't insert
// the first hash into the history
window.location.hash = "Again-No-back-button";
window.onhashchange = function(){
window.location.hash = "no-back-button";
}
</script>
None of the most-upvoted answers worked for me in Chrome 79. It looks like Chrome changed its behavior with respect to the Back button after version 75. See here:
https://support.google.com/chrome/thread/8721521?hl=en
However, in that Google thread, the answer provided by Azrulmukmin Azmi at the very end did work. This is his solution.
<script>
history.pushState(null, document.title, location.href);
history.back();
history.forward();
window.onpopstate = function () {
history.go(1);
};
</script>
The problem with Chrome is that it doesn't trigger onpopstate event unless you make browser action ( i.e. call history.back). That's why I've added those to script.
I don't entirely understand what he wrote, but apparently an additional history.back() / history.forward() is now required for blocking Back in Chrome 75+.
history.pushState(null, null, location.href);
window.onpopstate = function () {
history.go(1);
};
This is the way I could it accomplish it.
Weirdly, changing window.location didn't work out fine in Google Chrome and Safari.
It happens that location.hash doesn't create an entry in the history for Chrome and Safari. So you will have to use the pushstate.
This is working for me in all browsers.
history.pushState({ page: 1 }, "title 1", "#nbb");
window.onhashchange = function (event) {
window.location.hash = "nbb";
};
Try this to prevent the backspace button in Internet Explorer which by default acts as "Back":
<script language="JavaScript">
$(document).ready(function() {
$(document).unbind('keydown').bind('keydown', function (event) {
var doPrevent = false;
if (event.keyCode === 8 ) {
var d = event.srcElement || event.target;
if ((d.tagName.toUpperCase() === 'INPUT' &&
(
d.type.toUpperCase() === 'TEXT' ||
d.type.toUpperCase() === 'PASSWORD' ||
d.type.toUpperCase() === 'FILE' ||
d.type.toUpperCase() === 'EMAIL' ||
d.type.toUpperCase() === 'SEARCH' ||
d.type.toUpperCase() === 'DATE' )
) ||
d.tagName.toUpperCase() === 'TEXTAREA') {
doPrevent = d.readOnly || d.disabled;
}
else {
doPrevent = true;
}
}
if (doPrevent) {
event.preventDefault();
}
try {
document.addEventListener('keydown', function (e) {
if ((e.keyCode === 13)) {
//alert('Enter keydown');
e.stopPropagation();
e.preventDefault();
}
}, true);
}
catch (err) {
}
});
});
</script>
Here is another way to proceed. Instead of just trying to avoid the Back button functionality (which doesn't work reliably) we can add short SessionStorage conditions.
Say we have three different pages (page1, page2, and page3). On each page we got a link to click to acceed to the next one and we don't want the user to be able to go back to the previous page.
On the first page (page1.html) we create an SI (sessionStorage Item) with a dummy "prev" code and another one with "page1" code (SI "now"):
PAGE 1 <button onclick="goto()">PAGE 2</button>
-------------------
let thispage = '1' // Or 123456 if preferred or make sense
// You can replace this fixed 'thispage' value on each page with a script counting the clicks
// or any other way to increase its value, i.e., thispage++
// or what you want, even counting the url.length (lol)
sessionStorage.setItem('prev', '0') // Dummy code
sessionStorage.setItem('now', thispage)
// You can here make this page unreachable with page2/page3 SI same conditions
function goto(){
window.location = "page2.html"
}
On page2.html we use the usual NoBack script (if it works) and update SIs only if we're coming from page1:
PAGE 2 <button onclick="goto()">PAGE 3</button>
-------------------
// If it works, let it work :-)
history.pushState(null, null, location.href);
history.back();
history.forward();
window.onpopstate = function () {
history.go(1);
};
// else
let thispage = '2' // 456789
let thisprev = sessionStorage.getItem('now')
if(sessionStorage.getItem('prev')==thispage) {
console.log('USER is back on PAGE 2')
setTimeout(function() { goto() }, 1000); // Remove log + setTimeout
}
if(thisprev !== thispage) {
if(thisprev < thispage) {
console.log('USER is coming from PAGE 1')
sessionStorage.setItem('prev', thisprev)
sessionStorage.setItem('now', thispage)
}
else {
console.log('USER try to reload this page')
setTimeout(function() { goto() }, 1000);
}
}
function goto(){
window.location = "page3.html"
}
And on page3.html:
PAGE 3 <button onclick="goto()">BACK TO PAGE 1</button>
-------------------
history.pushState(null, null, location.href);
history.back();
history.forward();
window.onpopstate = function () {
history.go(1);
};
let thispage = '3' // 999999
let thisprev = sessionStorage.getItem('now')
if(sessionStorage.getItem('prev') == thispage) {
goto()
}
if(thisprev !== thispage) {
if(thisprev < thispage) {
sessionStorage.setItem('prev', thisprev)
sessionStorage.setItem('now', thispage)
}
else {
goto()
}
}
function goto(){
window.location = "page1.html" // Reinit test
}
The advantage is that even if the user manually reloads the previous page (if he had time to see and remember the URL) it still works. It was not tested on all devices, but seems to work fine on Firefox + Chrome + Edge Windows 10 and Firefox + Chrome on OS X.
This article on jordanhollinger.com is the best option I feel. Similar to Razor's answer but a bit clearer. Code below; full credits to Jordan Hollinger:
Page before:
<a href="/page-of-no-return.htm#no-back>You can't go back from the next page</a>
Page of no return's JavaScript:
// It works without the History API, but will clutter up the history
var history_api = typeof history.pushState !== 'undefined'
// The previous page asks that it not be returned to
if ( location.hash == '#no-back' ) {
// Push "#no-back" onto the history, making it the most recent "page"
if ( history_api ) history.pushState(null, '', '#stay')
else location.hash = '#stay'
// When the back button is pressed, it will harmlessly change the url
// hash from "#stay" to "#no-back", which triggers this function
window.onhashchange = function() {
// User tried to go back; warn user, rinse and repeat
if ( location.hash == '#no-back' ) {
alert("You shall not pass!")
if ( history_api ) history.pushState(null, '', '#stay')
else location.hash = '#stay'
}
}
}
For modal component in React project, the open or close of the modal, controlling browser back is a necessary action.
The stopBrowserBack: the stop of the browser back button functionality, also get a callback function. This callback function is what you want to do:
const stopBrowserBack = callback => {
window.history.pushState(null, "", window.location.href);
window.onpopstate = () => {
window.history.pushState(null, "", window.location.href);
callback();
};
};
The startBrowserBack: the revival of the browser back button functionality:
const startBrowserBack = () => {
window.onpopstate = undefined;
window.history.back();
};
The usage in your project:
handleOpenModal = () =>
this.setState(
{ modalOpen: true },
() => stopBrowserBack(this.handleCloseModal)
);
handleCloseModal = () =>
this.setState(
{ modalOpen: false },
startBrowserBack
);
For restricting the browser back event:
window.history.pushState(null, "", window.location.href);
window.onpopstate = function () {
window.history.pushState(null, "", window.location.href);
};
Some of the solutions here will not prevent a back event from occurring - they let a back event happen (and data held about the page in the browsers memory is lost) and then they play a forward event to try and hide the fact that a back event just happened. Which is unsuccessful if the page held transient state.
I wrote this solution for React (when react router is not being used), which is based on vrfvr's answer.
It will truly stop the back button from doing anything unless the user confirms a popup:
const onHashChange = useCallback(() => {
const confirm = window.confirm(
'Warning - going back will cause you to loose unsaved data. Really go back?',
);
window.removeEventListener('hashchange', onHashChange);
if (confirm) {
setTimeout(() => {
window.history.go(-1);
}, 1);
} else {
window.location.hash = 'no-back';
setTimeout(() => {
window.addEventListener('hashchange', onHashChange);
}, 1);
}
}, []);
useEffect(() => {
window.location.hash = 'no-back';
setTimeout(() => {
window.addEventListener('hashchange', onHashChange);
}, 1);
return () => {
window.removeEventListener('hashchange', onHashChange);
};
}, []);
I create one HTML page (index.html). I also create a one (mechanism.js) inside a script folder / directory. Then, I lay all my content inside of (index.html) using form, table, span, and div tags as needed. Now, here's the trick that will make back / forward do nothing!
First, the fact that you have only one page! Second, the use of JavaScript with span / div tags to hide and display content on the same page when needed via regular links!
Inside 'index.html':
<td width="89px" align="right" valign="top" style="letter-spacing:1px;">
<small>
<b>
<a href="#" class="traff" onClick="DisplayInTrafficTable();">IN</a>
</b>
</small>
[ <span id="inCountSPN">0</span> ]
</td>
Inside 'mechanism.js':
function DisplayInTrafficTable()
{
var itmsCNT = 0;
var dsplyIn = "";
for (i=0; i<inTraffic.length; i++)
{
dsplyIn += "<tr><td width='11'></td><td align='right'>" + (++itmsCNT) + "</td><td width='11'></td><td><b>" + inTraffic[i] + "</b></td><td width='11'></td><td>" + entryTimeArray[i] + "</td><td width='11'></td><td>" + entryDateArray[i] + "</td><td width='11'></td></tr>";
}
document.getElementById('inOutSPN').innerHTML =
"" +
"<table border='0' style='background:#fff;'><tr><th colspan='21' style='background:#feb;padding:11px;'><h3 style='margin-bottom:-1px;'>INCOMING TRAFFIC REPORT</h3>" +
DateStamp() +
" - <small><a href='#' style='letter-spacing:1px;' onclick='OpenPrintableIn();'>PRINT</a></small></th></tr><tr style='background:#eee;'><td></td><td><b>###</b></td><td></td><td><b>ID #</b></td><td></td><td width='79'><b>TYPE</b></td><td></td><td><b>FIRST</b></td><td></td><td><b>LAST</b></td><td></td><td><b>PLATE #</b></td><td></td><td><b>COMPANY</b></td><td></td><td><b>TIME</b></td><td></td><td><b>DATE</b></td><td></td><td><b>IN / OUT</b></td><td></td></tr>" +
dsplyIn.toUpperCase() +
"</table>" +
"";
return document.getElementById('inOutSPN').innerHTML;
}
It looks hairy, but note the function names and calls, embedded HTML, and the span tag id calls. This was to show how you can inject different HTML into same span tag on same page! How can Back/Forward affect this design? It cannot, because you are hiding objects and replacing others all on the same page!
How can we hide and display? Here goes:
Inside functions in ' mechanism.js ' as needed, use:
document.getElementById('textOverPic').style.display = "none"; //hide
document.getElementById('textOverPic').style.display = ""; //display
Inside ' index.html ' call functions through links:
<img src="images/someimage.jpg" alt="" />
<span class="textOverPic" id="textOverPic"></span>
and
<a href="#" style="color:#119;font-size:11px;text-decoration:none;letter-spacing:1px;" onclick="HiddenTextsManager(1);">Introduction</a>
I came across this, needing a solution which worked correctly and "nicely" on a variety of browsers, including Mobile Safari (iOS 9 at time of posting). None of the solutions were quite right. I offer the following (tested on Internet Explorer 11, Firefox, Chrome, and Safari):
history.pushState(null, document.title, location.href);
window.addEventListener('popstate', function (event)
{
history.pushState(null, document.title, location.href);
});
Note the following:
history.forward() (my old solution) does not work on Mobile Safari --- it seems to do nothing (i.e., the user can still go back). history.pushState() does work on all of them.history.pushState() is a url. Solutions which pass a string like 'no-back-button' or 'pagename' seem to work OK, until you then try a Refresh/Reload on the page, at which point a "Page not found" error is generated when the browser tries to locate a page with that as its URL. (The browser is also likely to include that string in the address bar when on the page, which is ugly.) location.href should be used for the URL.history.pushState() is a title. Looking around the web most places say it is "not used", and all the solutions here pass null for that. However, in Mobile Safari at least, that puts the page's URL into the history dropdown the user can access. But when it adds an entry for a page visit normally, it puts in its title, which is preferable. So passing document.title for that results in the same behaviour.history.pushState(null, null, document.URL);
window.addEventListener('popstate', function () {
history.pushState(null, null, document.URL);
});
This JavaScript code does not allow any user to go back (works in Chrome, Firefox, Internet Explorer, and Edge).
This code was tested with the latest Chrome and Firefox browsers.
<script type="text/javascript">
history.pushState(null, null, location.href);
history.back();
history.forward();
window.onpopstate = function () { history.go(1); };
</script>
//"use strict";
function stopBackSpace(e) {
var ev = e || window.event;
var obj = ev.target || ev.srcElement;
var t = obj.type || obj.getAttribute('type');
var vReadOnly = obj.getAttribute('readonly');
var vEnabled = obj.getAttribute('enabled');
// null
vReadOnly = (vReadOnly == null) ? false : vReadOnly;
vEnabled = (vEnabled == null) ? true : vEnabled;
// when click Backspace,judge the type of obj.
var flag1 = ((t == 'password' || t == 'text' || t == 'textarea') && ((vReadOnly == true || vReadOnly == 'readonly') || vEnabled != true)) ? true : false;
var flag2 = (t != 'password' && t != 'text' && t != 'textarea') ? true : false;
if (flag2) {
e.keyCode = 0;
e.cancelBubble = true;
return false;
}
if (flag1) {
e.keyCode = 0;
e.cancelBubble = true;
return false;
}
}
if (typeof($) == 'function') {
$(function() {
$(document).keydown(function(e) {
if (e.keyCode == 8) {
return stopBackSpace(e);
}
});
});
} else {
document.onkeydown = stopBackSpace;
}
<script src="~/main.js" type="text/javascript"></script>
<script type="text/javascript">
window.history.forward();
function noBack() {
window.history.forward();
}
</script>
You simply cannot and should not do this. However, this might be helpful:
<script type = "text/javascript" >
history.pushState(null, null, 'pagename');
window.addEventListener('popstate', function(event) {
history.pushState(null, null, 'pagename');
});
</script>
This works in my Google Chrome and Firefox.
I had this problem with React (class component).
And I solved it easily:
componentDidMount() {
window.addEventListener("popstate", e => {
this.props.history.goForward();
}
}
I've used HashRouter from react-router-dom.
This code will disable the back button for modern browsers which support the HTML5 History API. Under normal circumstances, pushing the back button goes back one step, to the previous page. If you use history.pushState(), you start adding extra sub-steps to the current page. The way it works is, if you were to use history.pushState() three times, then start pushing the back button, the first three times it would navigate back in these sub-steps, and then the fourth time it would go back to the previous page.
If you combine this behaviour with an event listener on the popstate event, you can essentially set up an infinite loop of sub-states. So, you load the page, push a sub-state, then hit the back button, which pops a sub-state and also pushes another one, so if you push the back button again it will never run out of sub-states to push. If you feel that it's necessary to disable the back button, this will get you there.
history.pushState(null, null, 'no-back-button');
window.addEventListener('popstate', function(event) {
history.pushState(null, null, 'no-back-button');
});
You can just put a small script and then check. It won't allow you to visit previous page.
This is done in JavaScript.
<script type="text/javascript">
function preventbackbutton() { window.history.forward(); }
setTimeout("preventbackbutton()", 0);
window.onunload = function () { null };
</script>
The window.onunload function fires when you try to visit back or previous page through browser.
<html>
<head>
<title>Disable Back Button in Browser - Online Demo</title>
<style type="text/css">
body, input {
font-family: Calibri, Arial;
}
</style>
<script type="text/javascript">
window.history.forward();
function noBack() {
window.history.forward();
}
</script>
</head>
<body onload="noBack();" onpageshow="if (event.persisted) noBack();" onunload="">
<H2>Demo</H2>
<p>This page contains the code to avoid Back button.</p>
<p>Click here to Goto <a href="noback.html">NoBack Page</a></p>
</body>
</html>
Just set location.hash="Something". On pressing the back button, the hash will get removed from the URL, but the page won't go back.
This method is good for preventing going back accidentally, but for security purposes you should design your backend for preventing reanswering.
Source: Stackoverflow.com