how to redirect with js and alert if turn in previous page?
<p>i want to redirect to a php page for example <code>example.php</code> and  make possible not to turn back to the first page,if try to turn i must alert the user.i dont want do delete the page from hisotry.
Any of that insrtuction:</p>

<pre><code>    window.open('example.php','_self') or
    location.href:example.php or
    header("location: example.php) or
or location.replace('example.php;)
</code></pre>

<p>cant do what i want.
is there any javascript method or php function to make that?
Thanks in advance!</p>