c# - Executing Javascript elementFromPoint through Selenium driver

Question

I am trying to implement an "object picker" to my Selenium based framework as is common on most commercial automation tools. To do this I am using a Javascript command to find the element at the mouse location, but I am not getting the element I expect.

If I am using ChromeDriver or InternetExplorerDriver the script always returns the header object. No matter what webpage I look at or the position of the mouse. Although it sounds like the script is taking the coordinates 0, 0 instead of the mouse position I have confirmed that Cursor.Position is sending the correct values.

If I am using FirefoxDriver I get an exception:

"Argument 1 of Document.elementFromPoint is not a finite floating-point value. (UnexpectedJavaScriptError)"

Can anyone see what I am doing wrong?

    private void OnHovering()
    {
        if (Control.ModifierKeys == System.Windows.Forms.Keys.Control)
        {
            IWebElement ele = null;
            try
            {
                // Find the element at the mouse position
                if (driver is IJavaScriptExecutor)
                    ele = (IWebElement)((IJavaScriptExecutor)driver).ExecuteScript(
                        "return document.elementFromPoint(arguments[0], arguments[1])", 
                        new int[] { Cursor.Position.X, Cursor.Position.Y });

                // Select the element found
                if (ele != null)
                    SelectElement(ele);
            }
            catch (Exception) { }
        }
    }

Thanks!

Answer 1

It's actually about how you are passing the coordinates into the script. Script arguments has to be specified separately as separate ExecuteScript() arguments. What was happening in your case is that you have basically specified one x argument which made it think that y should be considered a default 0 value. And at y=0 there is usually a header.

Instead of:

ele = (IWebElement)((IJavaScriptExecutor)driver).ExecuteScript(
                        "return document.elementFromPoint(arguments[0], arguments[1])", 
                        new int[] { Cursor.Position.X, Cursor.Position.Y });

You should do:

ele = (IWebElement)((IJavaScriptExecutor)driver).ExecuteScript(
                        "return document.elementFromPoint(arguments[0], arguments[1])", 
                        Cursor.Position.X, Cursor.Position.Y);