top.location.href = 'page.php';

The HTTP_REFERER will not get value populated. I tried to figure out why is this happening but seems it’s just the way it is. All other browsers Firefox, Chrome, Opera will set the referer properly, but IE6, IE7 and IE8 will not.

Though it is not a good practice to rely on HTTP_REFERER and you should probably not use it if you can, but nevertheless such kind of behaviour may cause strange bugs. If you happen to know why Internet Explorer behaves like this or know workaround to still have a referer value set when the browser redirects using javascript please leave a comment.

$array = array (0.1 => 'a', 0.2 => 'b');
echo count ($array);

It’s 1! In PHP array keys can only be made from integers and strings. Strangely enough it accepts floats too and casts them to integers!

While reviewing old code you might find stuf like:

my_sort_function(&$array);

Note that the $array is passed by reference. Yet again it turns out this kind of technique is deprecated and one should redeclare the function to accept the $array by reference. Common in PHP itself. Sadly I didn’t get a helpful warning that this type of technique is deprecated.

var value;
Form.getInputs(this.form, 'radio').each( function(input) { if (input.checked) { value = input.value }; });

document.getElementById('your_form_id').innerHTML += 'any text';

Your form will get reseted and there’s nothing more to validate.