console 命令行工具 X clear

console

window.onload=function(){
    //找到父元素
    var oTds=document.getElementsByTagName("td");

    for(var i=0;i<oTds.length;++i){
        oTds[i].onclick=function(){
            var oParent=this.parentNode;
            oParent.style.color="white";
            oParent.style.backgroundColor="lightskyblue";
        }
    }

    //找子元素和子节点
    var oUl=document.getElementById("list");
    var oChildElements=oUl.children;
    var oChildNodes=oUl.childNodes;//节点有空白文本节点
    console.log("line19:"+ oChildElements.length);
    console.log("line20:"+ oChildNodes.length);

   var oBtn=document.getElementById("btn");
   oBtn.onclick=function(){
       //删除最后一个子节点
     //  oUl.removeChild(oUl.lastChild);

       //删除元素节点
     //   if(oUl.lastChild.nodeType==3){
     //     oUl.removeChild(oUl.lastChild);
     //  }else{

      //  oUl.removeChild(oUl.lastChild);
     //  }
     //   oUl.removeChild(oUl.lastElementChild);
     //    oUl.removeChild(oUl.firstElementChild);
         oUl.removeChild(oUl.firstChild);

       //删除兄弟元素节点
       var ocss=oUl.children[1];
      // oUl.removeChild(ocss.previousElementSibling);
     //  oUl.removeChild(ocss.nextElementSibling);

        //删除兄弟节点
     //  var ocss=oUl.children[1];
     //  oUl.removeChild(ocss.previousSibling);
     //  oUl.removeChild(ocss.nextSibling);
   }

    //
}

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <style type="text/css">
        
    </style>
    <script>
       
    </script>
</head>
<body>
    <table>
        <caption>考试成绩表</caption>
        <tr>
            <td>小明</td>
            <td>80</td>
            <td>80</td>
            <td>80</td>
        </tr>
        <tr>
            <td>小红</td>
            <td>90</td>
            <td>90</td>
            <td>90</td>
        </tr>
        <tr>
            <td>小杰</td>
            <td>100</td>
            <td>100</td>
            <td>100</td>
        </tr>
    </table>

    <ul id="list">
        <li>HTML</li>
        <li>CSS</li>
        <li>JavaScript</li>
        <li>jQuery</li>
        <li>Vue.js</li>
    </ul>
    <button id="btn">删除</button>
</body>
</html>

table{
    border-collapse:collapse;
}
table,tr,td{
    border:1px solid gray;
}