Используйте следующий метод с Java + Selenium:
public boolean isPageReady(WebDriver driver){
boolean readyStateComplete = false;
while (!readyStateComplete){
JavascriptExecutor executor = (JavascriptExecutor) driver;
readyStateComplete = executor.executeScript("return document.readyState") == "complete";
}
return readyStateComplete;
}
Для C # + Selenium :
private void WaitUntilDocumentIsReady(TimeSpan timeout){
var javaScriptExecutor = WebDriver as IJavaScriptExecutor;
var wait = new WebDriverWait(WebDriver, timeout);
// Check if document is ready
Func<IWebDriver, bool> readyCondition = webDriver => javaScriptExecutor
.ExecuteScript("return (document.readyState == 'complete' && jQuery.active == 0)");
wait.Until(readyCondition);
}