Dom lesson1

时间：2023-03-08 17:14:33
<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>Insert title here</title>

</head>

<body>

<!-- 这个是demo -->

<a href="www.baidu.com">百度</a>

</body>

</html>

dom中有5个基本的对象：

Document  文档对象

Element  元素对象

Text  文本对象

Attribute  属性对象

Common  注释对象

Dom lesson1

Dom lesson1

dom中的所有对象在页面加载时候，都会由浏览器自动创建好，并放到内存中，所以我们操作dom，先要获得这些对象

demo:

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>Insert title here</title>

</head>

<body>

    姓名:

    <input type="text" id="userName" />

    <br /> 性别:

    <input type="text" id="userSex" />

    <br />

    <input type="button" value="提交" id="button" />

    <table border="1" id="userTable">

        <tr>

            <td>姓名</td>

            <td>性别</td>

        </tr>

    </table>

</body>

<script type="text/javascript">

document.getElementById("button").onclick=function(){

    var aa=document.getElementById("userName").value;

    var sex=document.getElementById("userSex").value;

    var td1=document.createElement("td");

    var td2=document.createElement("td");

    td1.innerHTML=aa;

    td2.innerHTML=sex;

    var tr=document.createElement("tr");

    tr.appendChild(td1);

    tr.appendChild(td2);

    document.getElementById("userTable").appendChild(tr);

};

</script>

</html>
<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>Insert title here</title>

</head>

<body>

请选择您的爱好!<br/>

<input type="checkbox" id="checkall">全选/全不选<br/>

<input type="checkbox" name="ch">游泳

<input type="checkbox" name="ch">唱个歌

<input type="checkbox" name="ch">玄虚<br/>

<input type="button" value="全选"/>

<input type="button" value="全不选"/>

<input type="button" value="反选"/>

</body>

<script type="text/javascript">

document.getElementById("checkall").onclick=function(){

    var chs=document.getElementsByName("ch");

    for(var i=0;i<chs.length;i++){

        chs[i].checked=this.checked;

    }

}

</script>

</html>
<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<title>无标题文档</title>

<style type="text/css">

</style></head>

<body>

<div style="border:1px dashed #E6E6E6;margin:150px 0px 0px 450px; width:350px; height:200px; background-color:#E6E6E6;">

<table width="285" height="169" border="0" align="left" cellpadding="0" cellspacing="0" style="margin:15px 0px 0px 15px;">

  <tr>

    <td width="126">

        <!--multiple="multiple" 能同时选择多个   size="10"  确定下拉选的长度-->

        <select name="first" size="10" multiple="multiple" class="td3" id="first">

          <option value="选项1">选项1</option>

          <option value="选项2">选项2</option>

          <option value="选项3">选项3</option>

          <option value="选项4">选项4</option>

          <option value="选项5">选项5</option>

          <option value="选项6">选项6</option>

          <option value="选项7">选项7</option>

          <option value="选项8">选项8</option>

        </select>

    </td>

    <td width="69" valign="middle">

       <input name="add"  id="add" type="button" class="button" value="-->" />

       <input name="add_all" id="add_all" type="button" class="button" value="==>" />

       <input name="remove"  id="remove" type="button" class="button" value="&lt;--" />

       <input name="remove_all" id="remove_all" type="button" class="button" value="&lt;==" />

        </td>

    <td width="127" align="left">

      <select name="second" size="10" multiple="multiple" class="td3" id="second">

         <option value="选项9">选项9</option>

      </select>

    </td>

  </tr>

</table>

</div>

</body>

<script type="text/javascript">

document.getElementById("add").onclick=function(){

    //1获得左侧的下拉选select

    var first = document.getElementById("first");

    var second =  document.getElementById("second");

    //2获得select中的所有option

    var options = first.options;

    //3遍历这些option 判断选中的状态

    for(var i = 0 ; i < options.length ; i++){

        var opt = options[i];

        if(opt.selected){

            //选中  ==> 将选中的option对象 添加到右侧select

            second.appendChild(opt);

            i--;

        }

            //没选中 ==> 什么都不做

    }

}

</script>

</html>

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