// NodeList of document's elements that match the selectors
const speakers = document.querySelectorAll(
  ".speakercolumn .title-heading-left"
);

// Create an Array from NodeList, because NodeList is not iterable with `map()`
const speakersArray = Array.from(speakers);

// Iterate through `speakersArray` to get `textContent` from every speaker (item of array)
const speakerTextContent = speakersArray.map((speaker) => speaker.textContent);

// copy the final result to clipboard
copy(speakerTextContent);

// The same function as above but without constants
copy(
  Array.from(
    document.querySelectorAll(".speakercolumn title-heading-left")
  ).map((speaker) => speaker.textContent)
);