So in essence I get the value of input, then try to divide into into different tags via the comma with this
var noteTags = document.getElementsByClassName("noteTag").value;
Tag = noteTags.split(",");
But in console, the split(",") is undefined
Edit: Sorry I forgot to mention that the noteTag element is input, does this change how the code works in any way?
There are two issues,
getElementsByClassName returns an array-like collection of elements (a NodeList).value it should be innerText.Try like below
var noteTags = document.getElementsByClassName("noteTag")[0].innerText;
Tag = noteTags.split(",");
You are using the split() method on an array. You are also trying to access the value property, whereby you should probably use innerText.
You can use querySelector then you dont need using a key[0] to select the element.
const noteTags = document.querySelector("#noteTag");
console.log(noteTags)
Tag = noteTags.innerHTML.split(",");
console.log(Tag)<div id="noteTag">en,jp,fr</div>