How can I detect if an html page element exists by using RoR RJS Template code?

Question

I tried several ways but all are failing.

Answer 1

As dbarker mentioned, you can use page['theElementID'] to test whether a specific HTML element exists based on its ID.

If your target element doesn't have an ID attribute, you can also check for it with a CSS selector, including class names. For example:

if page.select('div.comment').any?
    # Logic here if there is at least one comment
else
    # Logic for no comments
end

Documentation on page.select: http://api.rubyonrails.org/classes/ActionView/Helpers/PrototypeHelper/JavaScriptGenerator/GeneratorMethods.html#M001632

Answer 2

Actually, I couldn't get the

    if page[:element]
        # code here
    end

to work. Instead, I ended up using

    page << "if( $('element') ) {"
        # code here
    page << "}"

Answer 3

You can use the [ ] method of the JavascriptGenerator to find an element like this:

page['theElementId']

Here's a link to the details:

Module ActionView::Helpers::PrototypeHelper::JavaScriptGenerator::GeneratorMethods

Answer 4

You could use what dbarker said like this:

 if page['theElementId'].nil?
       # then have you logic here if the element does not exist
 else
       # if the element does exist
 end