export_github_repository_labels.js

// organization's repository labels (when all labels are expanded)
[...document.getElementsByClassName('js-new-label-name-input')]
  .filter((x) => /label-name-\d+/.test(x.id))
  .map((x) => x.id.substring(11))
  .map((x) => ({ 
    name: document.getElementById(`label-name-${x}`).value, 
    description: document.getElementById(`label-description-${x}`).value, 
    color: document.getElementById(`label-color-${x}`).value
  }))

// organization's repository labels (when all labels are collapsed)
[...document.getElementsByClassName('js-label-link')]
   .map((x) => ({ 
      name: x.firstElementChild.innerText.trim(),
      description: x.title,
      color: x.style.backgroundColor, // returned as RGB()
    }))
    .reduce((list, next) => { if (!list.find((x) => x.name == next.name)) { list.push(next); } return list; }, [])
    .filter((x) => x.name && x.name != 'Label preview')

// any other page with labels (issue list, issue view, PRs, etc.)
[...document.getElementsByClassName('IssueLabel')]
   .map((x) => ({ 
      name: x.innerText.trim(),
      description: x.title,
      color: x.style.backgroundColor, // returned as RGB()
    }))
    .reduce((list, next) => { if (!list.find((x) => x.name == next.name)) { list.push(next); } return list; }, [])