它使整個(gè)文本加粗。我只想將選定的文本加粗（絕對(duì)沒有 exec 命令）let boldBtn = document.getElementById('Bold-Btn');let boldClickListener = (event) =>{    event.preventDefault();    let selection = window.getSelection();    let final = `<span class="text-bold">${selection.focusNode.textContent}</span>`;    selection.anchorNode.parentElement.innerHTML=final;    console.log(selection);};boldBtn.addEventListener('click',boldClickListener);