Curl how to check if the page has loaded?

Question

PHP

How to check if the page has loaded when parsing through curl?
The site is sometimes dull and the page may not open.

Answer 1

If curl_exec returned control and did not set curl_errno, then the request was completed.
Between the states "request completed" and "page loaded" - the difference between the wheel and the car. It is necessary to clarify what "loaded page" means.