HTMLSlotElement.name

A string.

The following snippet is taken from our slotchange example (See it live).

let slots = this.shadowRoot.querySelectorAll('slot');
slots[1].addEventListener('slotchange', (e) => {
  let nodes = slots[1].assignedNodes();
  console.log(`Element in Slot "${slots[1].name}" changed to "${nodes[0].outerHTML}".`);
});

Here we grab references to all the slots, then add a slotchange event listener to the 2nd slot in the template — which is the one that keeps having its contents changed in the example.

Every time the element inserted in the slot changes, we log a report to the console saying which slot has changed, and what the new node inside the slot is.