1
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Well, I'm working with Selenium to scrape a webpage that has obfuscated class names (example <div class="example-gHJkLM">...)...

So I needed to create an extension method to get

public static ReadOnlyCollection<IWebElement> Descendants(this IWebElement element, bool hasChildren = false, int index = -1, string postAppend = "")
{
    var web = element.GetWebDriver(); // < 1ms
    var xpath = element.XPath(); // 5 ms

    return web.FindElements(By.XPath(xpath + "//" + (hasChildren ? "child::node()" : "*") + (index > -1 ? $"[{index + 1}]" : string.Empty) + postAppend)); // 64 ms
}

public static ReadOnlyCollection<IWebElement> GetNodesByContainingClass(this IWebElement element, string className,
    bool toLower = false, bool useFullHierarchy = false)
{
    return new ReadOnlyCollection<IWebElement>(element?.Descendants()
        .Where(n =>
            (toLower ? n.GetAttribute("class")?.ToLowerInvariant() : n.GetAttribute("class"))
            ?.Contains(className) == true).ToList()); // ????
}

public static IWebElement GetNodeByContainingClass(this IWebElement node, string className)
{
    return node?.GetNodesByContainingClass(className).FirstOrDefault();
}

Example usage:

            var watch = Stopwatch.StartNew();

            var welcomeMessage = messageBox
                .GetNodesByContainingClass(
                    "icon-", false, true)?
                .LastOrDefault();

            watch.Stop();
            Console.WriteLine($@"[Getting welcome message element] Ellapsed {watch.ElapsedMilliseconds} ms!", Color.Yellow);
  • messageBox is a IWebElement
  • I'm using Colorful.Console package

And this is what I got:

...

4 and 9 seconds to materialize a Where LINQ clause, seriously? I debugged the element?.Descendants() part and this has only 727 elements...

Can anyone guide me?

Also, I will be so thankfully if somebody suggests me a better approach to do this.

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2
  • \$\begingroup\$ for start, try this return new ReadOnlyCollection<IWebElement>(element?.Descendants().Where(n => n.GetAttribute("class").Equals(className, StringComparison.InvariantCultureIgnoreCase))); check the performance, and report. \$\endgroup\$
    – iSR5
    Commented Jan 29, 2020 at 3:45
  • \$\begingroup\$ But I'm not looking for Equals comparison, I'm checking Contains. \$\endgroup\$
    – z3nth10n
    Commented Jan 29, 2020 at 23:02

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