In the forms plugin: How to access formData array by name?

In the forms plugin: How to access formData array by name?

I have a form which I am validating in the beforeSubmit function.  Can the formData array be accessed by name?  That is, is there something like formData[name='foobar'] that I can write (to access the form element named foobar, or is it necessary to traverse the array looking for the item with a given name?  

Thanks.