How to deal with JavaScript Error: "e is null" when try to click on browser pop-up in Firefox

Question

When using the alert methods of selenium-webdriver, I encountered the JavaScript Error: "e is null"

Code:

browser = Watir::Browser.new :firefox
browser.alert.ok; sleep 5

Error:

Selenium::WebDriver::Error::UnknownError: [JavaScript Error: "e is null" {file: "file:///var/folders/f4/rz3xgqkj22zdyldyzrnyx4v40000gn/T/webdriver-profile20140731-47367-tyngix/extensions/[email protected]/components/command_processor.js" line: 7716}]'
[JavaScript Error: "e is null" {file: "file:///var/folders/f4/rz3xgqkj22zdyldyzrnyx4v40000gn/T/webdriver-profile20140731-47367-tyngix/extensions/[email protected]/components/command_processor.js"
line: 7716}]' when calling method: [nsICommandProcessor::execute]

Environment:

• 'selenium-webdriver', '2.42.0'
• Firefox 31.0
• MAC 10.9
• Ruby 2.0

Any advice would be very much appreciated. Thanks!

Spleen

Does an alert exist on the page? These javascript errors are related to the WebDriver API included within Firefox. What version of Watir-Webdriver are you using? – Glooming

Yes alert exists on the page. I use gem 'watir-webdriver' - 0.6.10 Any idea how to deal with this? – Spleen

Can you include the HTML of the page and the ruby code that causes the error? When I run your provided code, I get a Watir::Exception::UnknownObjectException pointing to Watir-Webdriver code because no alert exists when running your code sample. – Glooming

browser = Watir::Browser.new :firefox new_new = Onepage.new(:browser => browser) new_new.browser.alert.ok Did not manage to fix this yet... – Spleen

Without the HTML, it is difficult to determine what the error may be. – Glooming

Answer 1

Mine was caused by JavaScript alerts. There's an Ajax date picker that intermittently partially renders. While this is something that should be corrected in the application, in the mean time, I can handle it with:

try{
    driver.findElement(By.xpath("//span")).click();
   } catch (UnhandledAlertException uae) {
    driver.switchTo.alert().accept();
    driver.findElement(By.xpath("//span")).click();
   }

I'd also like to point out that I'm using WebDriver, so syntax may vary.

Ussery

I'd like to follow up. This answer partially fixed the problem. I also had to add Thread.sleep(6000) and InterruptedException to each connected method. I think you're using Ruby, so there may be an equivalent that you can reference elsewhere. – Ussery

Answer 2

So this isnt what you want to hear but this is my super hacky solution:

  target=browser.ul(:id => 'editor_sections').li(:index => j)
  target.drag_and_drop_by -300,200
  begin
    browser.button(:id => 'editor_panel_save').when_present.click
    puts "clicked save for module sidebar"
  rescue => e
    begin
      browser.alert.ok
      puts Thread.current["name"].white.on_red + ": No events for the " +sectionName + " module"
    rescue => e
    end
  end

As you can see the drag and drop event for me causes a jquery alert. I had the same problem as you did with the browser.alert.ok not always working. So I just wrapped it in an additional begin >> rescue block. The browser.alert.ok is actually called and the alert is dismissed AND that pesky random e is null error is ignored.

If anyone has an actual solution I'd love to see it.

Delcine

Answer 3

I am not sure about the Watir syntax, but following is the Java code to deal with Alerts.

Alert alert=driver.switchTo().alert();
alert.accept();

Bocock

Yes, the error is caused by browser.alert.ok which makes it a bit unusual case. – Spleen

Answer 4

We can't really answer this since the problem is in your javascript code (which is not attached).

Selenium::WebDriver::Error::UnknownError: [JavaScript Error: "e is null" {file: "file:///var/folders/f4/rz3xgqkj22zdyldyzrnyx4v40000gn/T/webdriver-profile20140731-47367-tyngix/extensions/[email protected]/components/command_processor.js" line: 7716}]'

Problem is in command_processor.js on line 7716.

Reichsmark

I know, but I think that file is a part of WatirWebDriver. Any other idea? – Spleen

This JS error is from the WebDriver extension included within Firefox. – Glooming