The Safari Back Button Problem

Autodidact_2051 0
Viewed 39841

I do some minor programming and web work for a local community college. Work that includes maintaining a very large and soul destroying website that consists of a hodge podge of VBScript, javascript, Dreamweaver generated cruft and a collection of add-ons that various conmen have convinced them to buy over the years.

A few days ago I got a call "The website is locking up for people using Safari!" Okay, step one download Safari(v3.1.2), step two surf to the site. Everything appears to work fine.

Long story short I finally isolated the problem and it relates to Safari's back button. The website uses a fancy-pants javascript menu that works in every browser I've tried including Safari, the first time around. But in Safari if you follow a link off the page and then hit the back button the menu no longer works.

I made a pared down webpage to illustrate the principle.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head><title>Safari Back Button Test</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body onload="alert('Hello');">
<a href="http://www.codinghorror.com">Coding Horror</a>
</body>
</html>

Load the page and you see the alert box. Then follow the link off the page and hit the back button. In IE and Firefox you see the alert box again, in Safari you do not.

After a vigorous googling I've discovered others with similar problems but no really satisfactory answers. So my question is how can I make my pages work the same way in Safari after the user hits the back button as they do in other browsers?

If this is a stupid question please be gentle, javascript is somewhat new to me.

safari javascript
12 Answers

Stefan's iframe solution works, but if that's not elegant enough, I find the following JavaScript also solves it:

window.onunload = function(){};

That is, if your menu is JavaScript, then you might prefer to solve this issue with JavaScript too.

The unload event handler definition idea came from this Firefox 1.5 article: https://developer.mozilla.org/en/Using_Firefox_1.5_caching.

Lee_Kowalkowski_309450

Please do not follow any of the advice that tells you to ignore the cache. Pages are cached for a reason -- to improve user experience. The methods you're using will make user experience worse, so unless you hate your users, don't do that.

The correct solution for Safari (Desktop and iOS) is to use the pageshow event instead of the onload event (See https://developer.mozilla.org/en-US/docs/Using_Firefox_1.5_caching for what these are).

The pageshow event will fire at the same time you expect the onload event to fire, but it will also work when pages are served via the cache. This appears to be what you want anyway.

user_763920

An iframe solves the problem:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head><title>Safari Back Button Test</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body onload="alert('Hello');">
<a href="http://www.codinghorror.com">Coding Horror</a>
<iframe style="height:0px;width:0px;visibility:hidden" src="about:blank">
this prevents back forward cache
</iframe>
</body>
</html>

more details

Stefan_Koenig_25850

I have no idea what's causing the problem but I know who might be able to help you. Safari is built on Webkit and short of Apple (who are not so community minded) the Webkit team might know what the issue is.

It's not a stupid question at all.

user_13846520

I've noticed something very similar. I think it is because Firefox and IE, when going back, are retrieving the page from the server again and Safari is not. Have you tried adding a page expiry/no cache header? I was going to look into it when I discovered the behaviour but haven't had time yet.

Stacey_Richards_11420

Try this
if(performance.navigation.type == 2) {
alert("Hello");
}

user_62750540

In my Angular application I used this condition to fix the problem. First I added onunload="" event handle to index.html lilke below

<body class="mat-typography" onunload="">
    <app-root></app-root>
</body>

then in my component ngOnInit method I added that code like below

  public ngOnInit(): void {
    window.onpageshow = (event) => {
        if (event.persisted) {
            document.body.style.display = "none";
            location.reload();
        }
    };
    ...
  }
user_105090560
Related