JS中的onchange事件不生效

<select class="list">
        <option value="5">每页5条</option>
        <option value="10">每页10条</option>
        <option value="15">每页15条</option>
        <option value="20">每页20条</option>
      </select>

// 创建切换显示条数事件
list.onchange = function() {
  let list = document.getElementsByClassName('list')[0];
  let index = list.selectedIndex;
  let val = list.options[index].value;
  page = val;
  num = 0;
  renders();
}

<select class="list" onchange="list()">
        <option value="5">每页5条</option>
        <option value="10">每页10条</option>
        <option value="15">每页15条</option>
        <option value="20">每页20条</option>
      </select>

// 创建切换显示条数事件
function list() {
  let list = document.getElementsByClassName('list')[0];
  let index = list.selectedIndex;
  let val = list.options[index].value;
  page = val;
  num = 0;
  renders();
}