DOM Object Properties - Skip All Radio / Checkbox Inputs That Aren't Checked

I was under the impression, via W3Schools that 'checked' is only a property of radio/checkbox input objects. I was trying out this code that loops through several different types of inputs:

Code:
//start loop
var elem = theInput[i]; //grab the input
if('checked' in elem && !elem.checked) { continue; }
//...do some other stuff
//end loop

As you can tell, I want to skip all radio/checkbox inputs that aren't checked because they are meaningless in my circumstance.....the problem is, it skips over EVERYTHING (that isn't checked) regardless of if it's a hidden input, text input, password input, etc..... I did a quick test:

[Code]...