I would like to do the following :

Hide a div <div id="one"> if a string (textstring) or if another div (<div id="two">) is included in the html code of one page of my web site.

The div to hide is as follows :

<div id="one">
<div id="two">

I am a beginner in both php and javascript.

I guess that it should be possible to test with innerhtml whether textstring or div id="two" is absent or present.
Then, if one of them is present, I also guess that a javascript code could hide the div id="one".

But unfortunately, I am unable to write the expected code.

So, I thank anyone in advance for any help in this matter.