PHP - Checking for IE, understanding $_SERVER['HTTP_USER_AGENT']

Question

I know some very light PHP and decided to start from the ground up and was looking at php.net http://php.net/manual/en/tutorial.useful.php On this page, it mentions in an example how to check for IE.

<?php
if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== FALSE) {
    echo 'You are using Internet Explorer.<br />';
}
?>

I have a very small test page made up that I'm going through the section here with and this is what I have written down...

<html>
    <head>
        <title>PHP startup testing page</title>
    </head>
    <body>
<?php 
        echo "<p>Hello World</p>";
        echo $_SERVER['HTTP_USER_AGENT']; //outputs the kind of browser the visitor is using.
        if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== FALSE) {
            echo 'You are using Internet Explorer.<br />';
        }
?>
    </body>
</html>

What I don't understand is why when I load this into Internet Explorer, the output onto my screen is Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko and the if statement thus returns nothing. Is there something very basic I'm not getting?

For what it is worth the user agent string is provided to PHP and is not reliable. If you need something specific I believe client side feature detection is going to serve you better. — Crackertastic, Oct 28 '15 at 20:21

score 2 · Accepted Answer · answered Oct 28 '15 at 20:21

2

IE 11 no longer uses MSIE in the user agent string, it is also bad practice to detect for a browser you should detect for features with libraries like Modernizer https://modernizr.com/, here is a link on IE 11 user agent strings https://msdn.microsoft.com/en-us/library/ms537503%28v=vs.85%29.aspx

answered Oct 28 '15 at 20:21

cmorrissey

8,493
2
23
27

Wow thanks a lot for that information! If you don't mind me asking then, what is the harm in searching the string for "Trident"? – JoeL Oct 28 '15 at 20:33
@JoeL take a look at this list of all the browsers that use `Trident` http://www.useragentstring.com/pages/Browserlist/, its much easier to make your site based on features of the browser then based on the browser, in addition users can change their User Agent String. – cmorrissey Oct 28 '15 at 20:46
point well taken. I will look into modernizr.com and how I can use that in my browser checks. This will be my last one and then I'll move on my merry way. Should I still be good with using php.net for beginner stuff? Or was this kind of an outlier in terms of outdated information. @cmorrissey – JoeL Oct 28 '15 at 20:52
1

php.net is great for reference, check out http://www.phptherightway.com/ for more information, and check your local book store for a book that was published in the past year that covers php, mysql, html, css, and js. – cmorrissey Oct 28 '15 at 20:55

PHP - Checking for IE, understanding $_SERVER['HTTP_USER_AGENT']

1 Answers1