const commentTestRE = /^<!--.*-->$/s
const commentRE = /<!--[^]*?-->/gm
function isComment(item) {
  return (
    typeof item === 'string' &&
    commentRE.test(item) &&
    !item.replace(commentRE, '').trim()
  )
}

function isCommentNew(item) {
  if (typeof item !== 'string' || !commentTestRE.test(item)) return false
  // if item is '<!---->' or '<!--[-->' or '<!--]-->', return true directly
  if (item.length <= 8) return true
  return !item.replace(commentRE, '').trim()
}

const str = '<div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div><div class="specs">Some Content</div>';