JavaScript实现复选框全选与全不选功能

<!DOCTYPE html>
<html>

 <head>
  <meta charset="UTF-8">
  <title>全选</title>
  <script>
   function myAll() {
    var all = document.getElementById("all");
    var oneList = document.getElementsByName("one");
    for(var i = 0; i < oneList.length; i++) {
     oneList[i].checked = all.checked;
    }
   }

   function myOne() {
    var all = document.getElementById("all");
    var oneList = document.getElementsByName("one");
    for(var i = 0; i < oneList.length; i++) {
     if(oneList[i].checked == false) {
      all.checked = false;
      return;
     }
    }
    all.checked = true;
   }
  </script>
 </head>

 <body>
  <table id="myTable" border="1" cellpadding="0" cellspacing="0" width="90%" height="180px">
   <tr>
    <th>全选<input id="all" type="checkbox" onclick="myAll()" /></th>
    <th>序号</th>
    <th>名称</th>
    <th>单价</th>
    <th>数量</th>
    <th>总计</th>
   </tr>
   <tr>
    <td><input name="one" type="checkbox" onclick="myOne()" /></td>
    <td>1</td>
    <td>物品A</td>
    <td>￥55</td>
    <td>1</td>
    <td>￥55</td>
   </tr>
   <tr>
    <td><input name="one" type="checkbox" onclick="myOne()" /></td>
    <td>2</td>
    <td>物品B</td>
    <td>￥70</td>
    <td>1</td>
    <td>￥70</td>
   </tr>
   <tr>
    <td><input name="one" type="checkbox" onclick="myOne()" /></td>
    <td>3</td>
    <td>物品C</td>
    <td>￥66</td>
    <td>1</td>
    <td>￥66</td>
   </tr>
  </table>
 </body>

</html>