When using the python3 kernel the following code works:

%%js
let b = document.createElement("b")
b.textContent="Hi there!"
element.append("A test:")
element.append(b)

and correctly outputs

A test:Hi there!

with Hi there! being bold.

However, when I switch to the javascript kernel and run the above code (without %%js) I get:

evalmachine.<anonymous>:1
let b = document.createElement("b")
        ^

ReferenceError: document is not defined
    at evalmachine.<anonymous>:1:9
    at Script.runInThisContext (node:vm:129:12)
    at Object.runInThisContext (node:vm:305:38)
    at run ([eval]:1020:15)
    at onRunRequest ([eval]:864:18)
    at onMessage ([eval]:828:13)
    at process.emit (node:events:527:28)
    at emit (node:internal/child_process:936:14)
    at processTicksAndRejections (node:internal/process/task_queues:84:21)

How can I successfully run the code snipped when using the js kernel?