How to test undefined in transcrypt

I need to test if a javascript object attribute exists.

For example to see if a jquery extension is available. The next line returns undefined in the browser console :

$("#myid").toc

I want to test this value in transcrypt, I tried :

getattr(S ("#myid"), "toc") is None

but it doesn't work :-/

Solution

The following will work:

HTML:

<html>
    <head>
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>    
    </head>
    <body>
        <div id="myid"></div>
        <script src="__javascript__/test.js"></script>
    </body>
</html>

Transcrypt:

__pragma__ ('alias', 'S', '$')

print (111, getattr (S ('#myid') [0], 'style') != None)
print (222, getattr (S ('#myid') [0], 'toc') != None)

console.dir (S ('#myid') [0])

It prints:

111 True
222 False
div#myid

As an alternative you can always embed JS in Transcrypt:

__pragma__ ('js', '{}', '''
   console.log (333, $("#myid")[0].style != undefined);
   console.log (444, $("#myid")[0].toc != undefined);
''')

Which prints:

333 true
444 false

I prefer the Python syntax, by the way. But in edge cases JS is always there as an escape, although you'll probably never need it.