<button type="button">button</button>

<script>
  const button = document.querySelector('button');
  
  button.addEventListener(
    'click',
    () => window.alert('1'),
  );
  button.addEventListener(
    'click',
    (event) => {
      
      // 尝试删除这行代码看看会发生什么
      event.stopImmediatePropagation();
      
      window.alert('2');
    },
  );
  button.addEventListener(
    'click',
    () => window.alert('3'),
  );
  button.addEventListener(
    'click',
    () => window.alert('4'),
  );
</script>