Get immediate first child element

Question

I'm writing a Chrome content script extension and I need to be able to target a specific element that, unfortunately, has no unique identifiers except its parent element.

I need to target the immediate first child element of parentElement. console.log(parentElement) reports both of the child elements/nodes perfectly, but the succeeding console logs (the ones that target the childNodes) always return an undefined value no matter what I do.

This is my code so far
^{(I have excluded the actual names to avoid confusion and extra, unnecessary explanation)}

function injectCode() {      var parentElement = document.getElementsByClassName("uniqueClassName");      if (parentElement && parentElement.innerHTML != "") {          console.log(parentElement);         console.log(parentElement.firstElementChild);         console.log(parentElement.firstChild);         console.log(parentElement.childNodes);         console.log(parentElement.childNodes[0]);         console.log(parentElement.childNodes[1]);      } else {          setTimeout(injectCode, 250);     }    } 

How do I select the first child element/node of parentElement?

Update:
parentElement.children[0] also has the same error as parentElement.childNodes[0].

Answer 1

Both these will give you the first child node:

console.log(parentElement.firstChild); // or console.log(parentElement.childNodes[0]); 

If you need the first child that is an element node then use:

console.log(parentElement.children[0]); 

Edit

Ah, I see your problem now; parentElement is an array.

If you know that getElementsByClassName will only return one result, which it seems you do, you should use [0] to dearray (yes, I made that word up) the element:

var parentElement = document.getElementsByClassName("uniqueClassName")[0];