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It is sometimes a good idea to find out where users can come from. When PHP is run the $_SERVER superglobal is always available and if the user has clicked on a link and landed on your page then the HTTP_REFERER value will be set. You can retrieve and view it on a test page like this.
if ( isset($_SERVER[ HTTP_REFERER ]) ) {
echo $_SERVER['HTTP_REFERER'];
}
Of course you might want to do something useful with this. For example, you might want to know what link a user clicked on when they broke your application.
I was writing unit tests for a API mapping function recently and came across this interesting issue. The code I was writing tests for was in a legacy codebase that I was making changes to, and it made sense to have some unit tests in there before I started work to ensure everything worked before and after.
Embedding image within pages of content helps both within the design of the page and when shared on social media. If you set up meta tags to point at a particular image then that image will appear when the page is shared on social media. This makes your page stand out more.
Generating a PDF document from a web page through PHP can be problematic. It's often something that seems quite simple, but actually generating the document can be difficult and time consuming.
Reflection is used to gather more information about code during the runtime of the program. This allows code to inspect itself and to make small modifications, which is useful in a variety of situations.
