How do I get search engine results programatically?  Some search engines use AJAX to display content and so the URL does not change. This makes it difficult to get result content from a search engine programatically.

Most search engines do not use AJAX.  But two popular ones that I am interested in is YANDEX and DUCKDUCKGO.  Both of these search engines use AJAX to advance beyond the first page of results.  How do I find a way to programatically access these pages?