作业要求：
效果：
代码：
<!DOCTYPE html><html><head><meta charset="utf-8"><title>作业2-全选</title><script src="utility.js" type="text/javascript" charset="utf-8"></script><style type="text/css">*{margin: 0px;padding: 0px;border: 0px solid black;}ul li{width: 80px;display: inline-block;border: 1px solid #000000;text-align: center;}ul li:first-child{width: 70px;}ul li:nth-child(2){width: 155px;}ul li:nth-child(3),ul li:nth-child(4){width: 75px;}#t1,td{border: 1px solid #000;width: 400px;border-collapse: separate;text-align: center;}input[type='button']{width: 110px;height: 50px;margin: 5px 130px;border: 1px solid;}</style></head><body><div id="b-box"><!-- 去除无序列表的点 --><ul style="list-style: none;"><li><input type="checkbox" name="" id="checkAll" value="" onclick="checkAll()">全选</input></li><li>学号</li><li>姓名</li><li>性别</li></ul><table id="t1"><tr><td><input type="checkbox" name="" value="" class="check"></input></td><td>334103</td><td>陈宸</td><td>男</td></tr><tr><td><input type="checkbox" name="" value="" class="check"></input></td><td>334103</td><td>陈宸</td><td>男</td></tr><tr><td><input type="checkbox" name="" value="" class="check"></input></td><td>334103</td><td>陈宸</td><td>男</td></tr><tr><td><input type="checkbox" name="" value="" class="check"></input></td><td>334103</td><td>陈宸</td><td>男</td></tr><tr><td><input type="checkbox" name="" value="" class="check"></input></td><td>334103</td><td>陈宸</td><td>男</td></tr></table><input type="button" name="" id="" value="雪藏" onclick="dis()"/><script type="text/javascript">function checkAll(){var check = document.getElementsByClassName("check");for(var i = 0;i < check.length; ++i){if(check[i].type == "checkbox"){check[i].checked = $("checkAll").checked;}}}function dis(){if(document.querySelector("[type = 'button']").value == '雪藏'){$("t1").style.color = "#fff"document.querySelector("[type = 'button']").value = '显示';}else{$("t1").style.color = "#000"document.querySelector("[type = 'button']").value = "雪藏";}}</script></div></body></html>
其中用到的utility.js文件：
function $(id){return document.getElementById(id);}function l(a){console.log(a);}
DOM练习文件：
/download/cc2855816075/80848641
注意：
1、去除无序列表li前面的点：
<ul style=“list-style: none;”>
