The function wp_is_mobile should accept also lower case strings as user agents

[giuse]

The actual version of the function wp_is_mobile is case sensitive and detects a mobile device only if the first letter of the User Agent is capital.

​https://developer.wordpress.org/reference/functions/wp_is_mobile/

For example, I would replace

strpos( $_SERVER['HTTP_USER_AGENT'], 'Mobile' ) !== false

with

strpos( strtolower( $_SERVER['HTTP_USER_AGENT'] ),'mobile' ) !== false

The same for the other User Agents.

[sabernhardt]

(I updated the version because the function has been around since WordPress 3.4 - changeset:20417)

Could the stripos function be appropriate and/or better here?

[johnbillion]

Which user agents does this affect?

[giuse]

I've opened this thread because W3 Total Cache was giving a problem with my plugin that uses this function.

If you save the option related to the User Agent of W3 Total Cache, it saves "mobile" instead of "Mobile". I know this is something that W3 Total Cache should solve, but what's the problem in adding a strtolower? The performance would be the same, and you would prevent issues with other plugins. Moreover, you never know if a certain browser uses "mobile" instead of "Mobile". This function would be more robust and prevent issues if it wasn't case sensitive.

I think it would be faster and easier adding strtolower than going ahead commenting on this function, we are not speaking about something that is a risk for performance or security. If you don't add strtolower I will replace this function with another one in my plugin, so if you don't want to add strtolower, I suggest closing this thread.

Consider that also other plugins may replace this function, this would be not good for the WP ecosystem if the reason is only a missing strtolower.

[giuse]

Or better. as suggested by @sabernhardt, you could replace strpos with stripos that is supported from PHP 5+, so no problem with stripos and really no difference in terms of performance.