mythofechelon mythofechelon -4 years ago 145
Javascript Question

Get immediate first child element

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
?

enter image description here

Update:

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

Answer Source

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];
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