如何仅向每个div追加一次

// HTML
<div id="div1">Div 1</div>
<div id="div2">Div 2</div>
<div id="div3">Div 3</div>

// JavaScript
const divs = document.querySelectorAll('div');
divs.forEach(div => {
  div.addEventListener('click', () => {
    div.innerHTML += ' Appended content';
  });
});

// HTML
<div id="div1" data-appended="false">Div 1</div>
<div id="div2" data-appended="false">Div 2</div>
<div id="div3" data-appended="false">Div 3</div>

// JavaScript
const divs = document.querySelectorAll('div');
divs.forEach(div => {
  div.addEventListener('click', () => {
    const appended = div.getAttribute('data-appended');
    if (appended === 'false') {
      div.innerHTML += ' Appended content';
      div.setAttribute('data-appended', 'true');
    }
  });
});

// HTML
<div id="div1">Div 1</div>
<div id="div2">Div 2</div>
<div id="div3">Div 3</div>

// JavaScript
const divs = document.querySelectorAll('div');
const appendedMap = new Map();
divs.forEach(div => {
  appendedMap.set(div, false);
  div.addEventListener('click', () => {
    if (!appendedMap.get(div)) {
      div.innerHTML += ' Appended content';
      appendedMap.set(div, true);
    }
  });
});