js题

<!--计算器-->请输入数字1： <input type="text" id="n1"><br>请输入数字2： <input type="text" id="n2"><br>请选择运算符： <select name="" id="fh"><option value="+">+</option><option value="-">-</option><option value="*">*</option><option value="/">/</option></select><br><button id="btn1" onClick="a()">计算</button>结果为： <span id="jg1"></span><script>function a(){var n1 = +document.getElementById("n1").value;var n2 = +document.getElementById("n2").value;var fh = document.getElementById("fh").value;var btn1 = document.getElementById("btn1");var str = "";switch(fh){case "+":str = n1 + n2;break;case "-":str = n1 - n2;break;case "*":str = n1 * n2;break;case "/":str = n1 / n2;break;}document.getElementById("jg1").innerHTML = str;}</script><!--动态时钟--><div id="st"></div><script>function getDate(){ ???????var date = new Date(); ???????var date1 = date.toLocaleString(); ???????var div1 = document.getElementById("st"); ???????div1.innerHTML = date1; ???????} ???????setInterval("getDate()",1000);</script><!--全选全不选--><table width="300" border="1"><tr><th><input type="checkbox" id="qx" onClick="qx()">全选</th><th>姓名</th><th>性别</th><th>年龄</th></tr><tr><td><input type="checkbox" class="xz"></td><td>默默</td><td>女</td><td>20</td></tr><tr><td><input type="checkbox" class="xz"></td><td>笨笨</td><td>女</td><td>20</td></tr><tr><td><input type="checkbox" class="xz"></td><td>娜娜</td><td>女</td><td>20</td></tr></table><script>function qx(){var qx = document.getElementById("qx");var zhi = qx.checked;var xz = document.getElementsByClassName("xz");for(var i = 0;i < xz.length;i++){xz[i].checked = zhi;}}</script><!--轮播图--><button onClick="sy()" id="syz">上一张</button><img src="imgs/300 (1).jpg" ?id="tp"><button onClick="xy()" id="xyz">下一张</button><script>var syz = null;var xyz = null;var tp = null;var imgs = [];var n = null;var tm = null;window.onload = function(){syz = document.getElementById("syz");xyz = document.getElementById("xyz");tp = document.getElementById("tp");imgs = ["imgs/300 (1).jpg","imgs/300 (2).jpg","imgs/300 (3).jpg","imgs/300 (4).jpg","imgs/300 (5).jpg"];n = 0;tm = setInterval(xy,3000);tp.onmouseover = function(){clearInterval(tm);}tp.onmouseout = function(){tm = setInterval(xy,3000);}}function sy(){n--;if(n < 0){n = imgs.length - 1;}for(var i = 0;i < imgs.length;i++){tp.setAttribute("src",imgs[n]);}}function xy(){n++;if(n > imgs.length - 1){n = 0;}for(var i = 0;i < imgs.length;i++){tp.setAttribute("src",imgs[n]);}}</script><!--36选7--><div id="szs"></div><button onClick="ks()">开始</button><span id="sjjg"></span><script>function xxx(){var str = "";for(var i = 1;i < 37;i++){str += i + ‘,‘;}document.getElementById("szs").innerHTML = str;}xxx();function ks(){var stt = "";for(i = 0;i < 7;i++){var zhi = parseInt(Math.random()*36)+1;if(stt.indexOf(zhi) == -1){stt += zhi + ",";}else{i--;}}document.getElementById("sjjg").innerHTML = stt;}</script><!--验证码--><br>验证码： <span id="mmm"></span><br>请输入验证码： <input type="text" id="srrr"> <br><button onClick="yy()">验证</button><span id="nnn"></span><script>function ll(){var zfs = "123456asdfgh";zfs = zfs.split("");var str = "";for(var i = 0;i < 4;i++){var zhi = parseInt(Math.random()*zfs.length);str += zfs[zhi];}document.getElementById("mmm").innerHTML = str;}ll();function yy(){var yzm = document.getElementById("mmm").innerHTML;var srr = document.getElementById("srrr").value;if(yzm == srr){document.getElementById("nnn").innerHTML = "输入正确";}else{document.getElementById("nnn").innerHTML = "输入错误";}}</script><!--表格添加删除--><table width="300" border="1" id="tab"><tr><th onClick="change(this)">年级</th><th onClick="change(this)">姓名</th><th onClick="change(this)">性别</th><th onClick="change(this)">操作</th></tr><tr><td onClick="change(this)">1</td><td onClick="change(this)">找找</td><td onClick="change(this)">女</td><td><button onClick="del(this)" class="scc">删除</button></td></tr><tr><td onClick="change(this)">2</td><td onClick="change(this)">等等</td><td onClick="change(this)">女</td><td><button onClick="del(this)" class="scc">删除</button></td></tr><tr><td onClick="change(this)">3</td><td onClick="change(this)">肉肉</td><td onClick="change(this)">女</td><td><button onClick="del(this)" class="scc">删除</button></td></tr></table><button onClick="add()" id="cre">添加</button><script>function add(){var tab = document.getElementById("tab");tab.innerHTML += `<tr><td onClick="change(this)">4</td><td onClick="change(this)">星星</td><td onClick="change(this)">女</td><td><button onClick="del(this)" class="scc">删除</button></td></tr>`}function del(obj){obj.parentElement.parentElement.remove();}</script>