Question

I need to check for an attribute inside the Jquery Mobile transition data object. The attribute can either be undefined or has a value of dialog or some other value.

Originally I only checked like this:

$(document).on( "pagebeforechange", function( e, data ) {
    if(  A && B && data.options.role != "dialog" ){
        // do something
        }
     });

However, this way I never enter the if-clause when data.options.role is undefined. I’m currently trying like this but am not really getting anywhere:

$(document).on( "pagebeforechange", function( e, data ) {
    if(  A && B && data.options.role != "undefined" && data.options.role != "dialog" ){
        // do something
        }
     });

Question
How can I make sure the value is queries and passes into the IF clause if it’s either undefined or has a value, which is not dialog?

Thanks for help!

Answer 1

If you meant undefined type of javascript, for that you need to use typeof like this:

if(  A && B && typeof data.options.role != "undefined" &&
      data.options.role != "dialog" )

You also need to make sure that A and B are coming truthy too.