Adding copy/code to specific donation pages
There are two "better ways" you can try.

First, you can put a template override into a folder with the contribution page ID.  So if the current override is at &lt;overrides&gt;/templates/CRM/Contribution/Form.php, then &lt;overrides&gt;/templates/CRM/Contribution/1/Form.php will only override page ID 1.

However, template overrides aren't very maintainable, and they're pretty hacky.

Instead, you can create an extension.  You can use hook_civicrm_buildForm like so:

function myextension_civicrm_buildForm( $formName, &amp;$form ) { 
  if ($formName == 'CRM_Contribution_Form_Main' ){
    CRM_Core_Resources::singleton()-&gt;addScriptFile('org.example.myextension', 'js/myjavascript.js');
  }
}


This technique is covered in greater detail in the Resources Reference.