Odd JavaScript getElementsByName undefined error

Question

Okay, I've seriously got to be missing something or I'm crazy. Here's the code I'm having an issue with, it is inside an onchange event:

console.log( (this.parentNode.parentNode) );
// fine prints the elements

console.log( (this.parentNode.parentNode).getElementsByName('otherposition[]') );
// gives me undefined error

(this.parentNode.parentNode).getElementsByName('otherposition[]')[0].style.opacity = '1';
// same error.

Answer 1

getElementsByName是document一种方法，元素没有这种方法。