Checking whether Paragraph Style name exists in document

In JS, I have an object of shorthand keys and paragraph style names, like so:

  var styles = {

     BDY: "Body Text",

      HED1: "Headline 1",

     HED2: "Headline 2",

     etc. 

  }

Is there a way to quickly check whether a name is present in the document, without having to loop through all the styles in the document?

I tried something like:

var docStyles = doc.paragraphStyles;    

for ( var key in styles ) {

          if ( typeof docStyles[ styles[key] ] == "undefined" ) ...

   }

But the invalid name still is defined, it's still an instanceof PargraphStyle, but of course, if I try to use it later in the script, I get an error.

Any thoughts, or do I have to call allParagraphStyles, and loop through that to figure out if the name matches one of those in the list?