1.a 标签的用法
<a href="//google.com">谷歌网页链接</a>
<a href="http//google.com">谷歌网页链接</a>
<a href="https//google.com">谷歌网页链接</a>
<a href="/a/b/c.html">子目录c</a>
<a href="a/b/c.html">子目录c</a>
<a href="index2.html">当前目录index2</a>
<a href="./index2.html">当前目录index2</a>
<a href="javascript:alert(1);">js伪协议</a>
<a href="mailto:736264660@qq.com">发邮件给我</a>
<a href="#">返回顶部</a>
<a href="tel:157">打电话给我</a>
<a href="#aa">返回id为aa的地方</a>
<a href="#" target="_blank">新页面打开</a>
<a href="#" target="_self">当前页面打开</a>
<a href="#" target="_top">顶层页面打开</a>
<a href="#" target="_parent">父级页面打开</a>
<a href="#" target="xxx">有xxx就用xxx打开，没有就创建xxx</a>
2.img 标签的用法
<img id="x" src="壁纸.jpg" alt="马修" width="500px">插入图片
<script>
x.onload=function(){
console.log("图片加载成功");
};
x.onerror=function(){
console.log("图片加载失败");
x.src="/壁纸.jpg";
};
</script>
3.table 标签的用法
<table>
<thead></thead>
<tr>
<th></th>
<th>小红</th>
<th>小明</th>
<th>小李</th>
</tr>
<tbody>
<tr>
<th>数学</th>
<td>61</td>
<td>91</td>
<td>85</td>
</tr>
<tr>
<th>数学</th>
<td>61</td>
<td>91</td>
<td>85</td>
</tr>
<tr>
<th>数学</th>
<td>61</td>
<td>91</td>
<td>85</td>
</tr>
<tr>
<th>数学</th>
<td>61</td>
<td>91</td>
<td>85</td>
</tr>
</tbody>
<tfoot>
<tr>
<th>总分</th>
<td>200</td>
<td>200</td>
<td>200</td>
</tr>
</tfoot>
</table>
样式：
table-layout:auto(自动调节),fixed(等宽)
border-collapse:collapse(边框合并)
border-spacing:0(边框间距为0)
