PHP Check if page contains
<p>I'm looking for a quick code/function that will detect if a page contains a certain thing.</p>

<p>It's for a new project I'm working on.</p>

<p>Basically, the user will paste a simple javascript code into their pages, but I need to make sure they do.</p>

<p>I need a code that will scan through a specific webpage url and find the code I provided.</p>

<p>Thanks!</p>
