原理性样例案例一：全选等
运用知识点：ondblclick=（）| onclick | 寻找标签属性及判断和函数的应用 
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> </head> <body> <div> <input type="button" value="全选" ondblclick="checkAll()" /> <input type="button" value="取消" ondblclick="cancleAll()" /> <input type="button" value="反选" ondblclick="reverseAll()" /> </div> <table> <thead> <tr> <th>序列号</th> <th>用户名</th> <th>年龄</th> </tr> </thead> <tbody id="tb"> <tr> <td><input class="c1" type="checkbox"/></td> <td>alex</td> <td>19</td> </tr> <tr> <td><input class="c1" type="checkbox"/></td> <td>alex</td> <td>19</td> </tr> <tr> <td><input class="c1" type="checkbox"/></td> <td>alex</td> <td>19</td> </tr> <tr> <td><input class="c1" type="checkbox"/></td> <td>alex</td> <td>19</td> </tr> </tbody> </table> <script> //全选的话先获取所有的input标签属性，然后全部为true function checkAll(){ var tb = document.getElementById('tb');//获取tb，也就是身体 var checks = tb.getElementsByClassName('c1'); //[第一个，2，3，4，5]checked = true for (var i=0;i<checks.length; i++){ var current_check = checks[i];//得到每个input的值并赋一个变量名 current_check.checked = true; } } function cancleAll(){ var tb = document.getElementById('tb');//获取tb，也就是身体 var checks = tb.getElementsByClassName('c1'); //[第一个，2，3，4，5]checked = true for (var i=0;i<checks.length; i++){ var current_check = checks[i];//得到每个input的值并赋一个变量名 current_check.checked = false; } } function reverseAll(){ var tb = document.getElementById('tb');//获取tb，也就是身体 var checks = tb.getElementsByClassName('c1'); //[第一个，2，3，4，5]checked = true for (var i=0;i<checks.length; i++){ var current_check = checks[i];//得到每个input的值并赋一个变量名 if(current_check.checked <!--这个地方如果为true-->){ current_check.checked = false; }else{ current_check.checked = true; } } } </script> </body></html>案例二：单选
要求只能选一个，并且用js可以改变其选项 运用知识点：getElementsByTagName | checked | 互斥 
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> </head> <body> <ul> <li><input type="radio" name="g" value="11" />男</li> <li><input type="radio" name="g" value="22" />女</li> <li><input type="radio" name="g" value="33" />女司机</li> </ul> <!--radio = document.getElementsByTagName('input') [<input type="radio" name="g" value="11">, <input type="radio" name="g" value="11">, <input type="radio" name="g" value="11">] radio[1] <input type="radio" name="g" value="11"> xo = radio[1] <input type="radio" name="g" value="11"> xo.value "11" xo.checked false xo.checked = true true--> </body></html>案例三：克隆 
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> </head> <body> <h2 id="h1">333 <span>123</span> <a>123</a> </h2> <div id="container"> <div class="item">1 </div> <div class="item">2</div> </div> <script> var h = document.getElementById('h1'); var c = document.getElementById('container') //c.appendChild(h);//直接添加到2下面了// var newH = h.cloneNode(true);//不加true,只克隆格式// c.appendChild(newH);加true后完整克隆到2下面了 </script> </body></html>案例四：自定义属性，获取自定义属性并改变标签内容  
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> </head> <body> //可以构造出一种选择器 <input type="button" onclick="Func()" value="点我啊" /> <div id='i1'> <div class="c1">123</div> <div class="c1" alex='sb'>123</div> <div class="c1" alex='sb'>123</div> <div class="c1" alex='sb'>123</div> <div class="c1">123</div> <div class="c1" alex='sb'>123</div> <div class="c1">123</div> <div class="c1" alex='sb'>123</div> <div class="c1">123</div> </div> <script> function Func(){ //i1所有孩子，循环每一个孩子，判断如果alex='sb' var i1 = document.getElementById('i1') var divs = i1.children for ( var i =0; i<divs.length;i++){ var current_div = divs[i]; var result = current_div.getAttribute('alex')//得到属性 //console.log(result); if (result == 'sb'){ current_div.innerText = '456'; } } } </script> </body></html>案例五：获取输入框内的值三种方法 
<!DOCTYPE html><html><head> <title></title> <meta charset="utf-8" /></head><body> <div id="inp"> </div> <input type="text" class="aa"/> <input type="button" value="添加" onclick="Func();" /> </div> <div id="lis"> <ul> <li>红烧肉</li> <li>红烧肘子</li> <li>红烧鱼</li> </ul> </div> <script> var inp_aa = document.getElementsByClassName('aa'); inp_aa[0].value = '红烧带鱼';//相当于在输入框输入内容 </script></body></html><!DOCTYPE html><html><head> <title></title> <meta charset="utf-8" /></head><body> <div id="inp"> </div> <input type="text" class="aa"/> <input type="button" value="添加" onclick="Func();" /> </div> <div id="lis"> <ul> <li>红烧肉</li> <li>红烧肘子</li> <li>红烧鱼</li> </ul> </div> <script> var c = document.querySelector('.aa');//查询选择器 .是区别id，标签的语法 c.value = '红烧茄子'; </script></body></html>方法二：查询 <!DOCTYPE html><html><head> <title></title> <meta charset="utf-8" /></head><body> <div id="inp"> </div> <input type="text" id="aa"/> <input type="button" value="添加" onclick="Func();" /> </div> <div id="lis"> <ul> <li>红烧肉</li> <li>红烧肘子</li> <li>红烧鱼</li> </ul> </div> <script> var c = document.getElementById('aa'); c.value = '红烧茄子'; </script></body></html>方法三：id 案例六： 
//'beforeBegin'、'afterBegin'/ 'beforeEnd'/'afterEnd' <!DOCTYPE html><html> <head> <title></title> <meta charset="utf-8" /> </head> <body> <div id="inp"> </div> <input type="text" /> <input type="button" value="添加" onclick="addElen(this)" /> </div> <div> <ul id="lis"> <li>红烧肉</li> <li>红烧肘子</li> <li>红烧鱼</li> </ul> </div> <script> function addElen(ths) { var aaa = ths.previousElementSibling.value; // alert(aaa) var list_li = document.getElementById("lis"); // alert(list_li) var bbb = "<li>" +aaa+ "</li>"; // alert(bbb) list_li.insertAdjacentHTML("beforeEnd", bbb) } </script> </body></html><!DOCTYPE html><html> <head> <title></title> <meta charset="utf-8" /> </head> <body> <div id="inp"> </div> <input type="text" /> <input type="button" value="添加" onclick="addElen(this)" /> </div> <div> <ul id="lis"> <li>红烧肉</li> <li>红烧肘子</li> <li>红烧鱼</li> </ul> </div> <script> function addElen(ths){ var aaa = ths.previousElementSibling.value; //获取input的值 var list_li = document.getElementById("lis"); //获取ul var tag = document.createElement('li');//创建li tag.innerText = aaa; //赋予tag也就是新的li标签里面的值是输入的input的值 list_li.insertBefore(tag, list_li.children[-1])//根据索引插入需要位置的值 } </script> </body></html><!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> </head> <body> <div> <input type="text" /> <input type="button" value="添加" onclick="AddElement(this)" /> </div> <div> <ul id="commentList"> <li>alex</li> <li>eric</li> </ul> </div> <script> function AddElement(ths){ //获取输入的值 var val = ths.previousElementSibling.value; var commentList = document.getElementById('commentList') //第一种形式 var str = "<li>" + val + "</li>" //'beforeBegin'、'afterBegin'/ 'beforeEnd'/'afterEnd' //beforeEnd 内部最后 //beforeBegin 外部上边 //afterBegin 内部贴身 //afterEnd 外部贴身// commentList.insertAdjacentHTML("beforeEnd", str) //第二种方式，元素的方式 var tag = document.createElement('li'); tag.innerText = val; var temp = document.createElement('a'); temp.innerText = '百度'; temp.href = "http://www.baidu.com"; tag.appendChild(temp); commentList.insertBefore(tag,commentList.children[1]); console.log(commentList.children[1]) } </script> </body> </html>案例七：  
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> <style> input{ height: 40px; } .gg{ color: gray; } .bb{ color: black; } </style> </head> <body> <p>当鼠标进入是，移除内容</p> <p>当输入表退出时，添加内容</p> <input type="text" class="gg" value="请输入内容" onfocus="Focus(this)" onblur="Blur(this)" /> <script> function Focus(ths){ //查找的第一种方式 //document。。 //第二种方式this //ths //ths.className = 'bb' var current_val = ths.value; if (current_val == "请输入内容"){ ths.value = ""; ths.className = 'bb'; } } function Blur(ths) { var current_val = ths.value; if (current_val == "请输入内容" || current_val.trim().length == 0 ){ ths.value = '请输入内容'; ths.className = 'gg'; } } </script> </body></html>案例八：头部菜单 
<!DOCTYPE html><html> <head> <title></title> <meta charset="utf-8" /> <style> .pg_top .menu { background-color: gold; width: 400px; height: auto; position: absolute; left: 200px; } .item { float: left; margin: 10px 0; padding: 0 20px; font-size: 25px; } .content { position: absolute; left: 200px; top: 58px; background-color: burlywood; width: 400px; height: 200px; } .hide { display: none; } .bk { background-color: greenyellow; } </style> </head> <body> <div class="pg_top"> <div class="menu"> <div class="item" con="h1" onclick="Show(this)">十八里店</div> <div class="item" con="h2" onclick="Show(this)">簋街</div> <div class="item" con="h3" onclick="Show(this)">后海</div> </div> <div id="content" class="content"> <div con="h1">烤全羊</div> <div class="hide" con="h2">麻辣龙虾</div> <div class="hide" con="h3">相约酒吧</div> </div> </div> <script> function Show(ths) { //当我点这个标签的时候,其他标签的背景色变没 var baba = ths.parentElement.children; //获取到了每个子元素 var target = ths.getAttribute('con'); for (i = 0; i < baba.length; i++) { if (ths == baba[i]) { //做判断， ths.classList.add('bk') //添加属性 } else { baba[i].classList.remove('bk') //删除属性 } } //内容 var current_con = document.getElementById('content').children; console.log(current_con) for (j=0; j<current_con.length;j++) { var s_att = current_con[j].getAttribute('con') if (target == s_att ) { current_con[j].classList.remove('hide'); }else{ current_con[j].className = 'hide'; } } } </script> </body></html><!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> <style> ul{ list-style: none; padding: 0; margin: 0; } ul li{ float: left; background-color: #2459a2; color: white; padding: 8px 10px; } .clearfix:after{ display: block; value:'111'; content: '.'; height: 0; /*visibility: hidden;*/ clear: both; } .hide{ display: none; } .tab-menu .title{ background-color: #dddddd; } .tab-menu .title .active{ background-color: white; color: black; } .tab-menu .content{ border: 1px solid #dddddd; min-height: 150px; } </style> </head> <body> <div style="width:400px; margin: 0 auto;"> <div class="tab-menu"> <div class="title clearfix"> <ul> <li target='h1' class="active" onclick="Show(this)">十八里店</li> <li target='h2' onclick="Show(this)">簋街</li> <li target='h3' onclick="Show(this)">十刹海</li> </ul> </div> <div class="content" id="content"> <div con="h1">烤羊腿</div> <div con="h3" <!--class="hide"-->>油焖小龙虾</div> <div con="h2" <!--class="hide"-->>香甜鸡尾酒</div> </div> </div> </div> <script> function Show(ths){ //ths表示当前标签 var target = ths.getAttribute('target')//h3 //给自己添加样式active //兄弟们去掉 ths.className = 'active'; var brothers = ths.parentElement.children; for(var i=0;i<brothers.length;i++){ if ( ths == brothers[i]){ }else{ brothers[i].removeAttribute('class') } } //操作内容 var contents = document.getElementById('content').children; console.log(contents) for (var j=0;j<contents.length;j++){ var current_content = contents[j]; console.log(current_content) var con = current_content.getAttribute('con') if (con == target){ current_content.classList.remove('hide'); }else{ current_content.className="hide"; } } } </script> </body></html>案例九：返回顶部
主要知识点：onscroll 和document.body.scrollTop; 
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> <style> .go-top{ position: fixed; right: 20px; bottom: 19px; width: 40px; height: 40px; background-color: darkgoldenrod; color: white; } .hide{ display: none; } </style> </head> <body onscroll="Func();"> <div id="i1" style="height: 2000px; background-color: greenyellow;"> <h1>asdfafdasdf</h1> </div> <div id="i2" class="go-top hide"> <a href="javascript:void(0)" onclick="goTop();">返回顶部</a> </div> <script> function Func(){ var scrollTop = document.body.scrollTop;//body的滚动高度 var ii = document.getElementById('i2'); if(scrollTop>100){ ii.classList.remove('hide');//移除就是显示 }else{ ii.classList.add('hide'); } } function goTop(){ document.body.scrollTop=0; } </script> </body></html> 案例十：
主要知识点： //scroll 滚动；卷轴的意思
// scrollTop: 滚动条距离顶部高度
// scrollHeight: 文档高度:自身+padding
// clientTop: 边框高度
// clientHeight: 当前范围可视的高度:自身 + padding
//offset 印刷的意思
// offsetTop: 当前标签距离"顶部"的高度(body)
// 如果他的上一级没有postion,如果有则按照position的标签为主
// offsettHeight: 自身范围的高度:自身+padding+border 
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> </head> <body> <div style="height: 20px;background-color: green;"></div><!--头部--> <div style="border: 5px solid pink;padding: 10px;"><!--body--> <div> <div id="xo" style="height: 200px;overflow: auto;width: 400px;margin: 0 auto;border: 15px solid red;padding: 3px;" > <div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div> <div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div> <div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div> <div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div> <div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div> <div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div> <div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div><div>sdf</div> <div>sdf</div><div>sdf</div> </div> </div> </div> <script> var ii = document.getElementById('xo') console.log(ii.scrollTop) console.log(ii.scrollHeight) console.log(ii.clientTop) console.log(ii.clientHeight) console.log(ii.offsetTop) console.log(ii.offsetHeight) //scroll 滚动；卷轴的意思// scrollTop: 滚动条距离顶部高度// scrollHeight: 文档高度:自身+padding// clientTop: 边框高度// clientHeight: 可见范围的高度:自身 + padding //offset 印刷的意思// offsetTop: 当前标签距离"顶部"的高度(body)// 如果他的上一级没有postion,如果有则按照position的标签为主// offsettHeight: 可见范围的高度:自身+padding+border </script> </body></html>好了，暂时就介绍到这里希望大家多写多练，主要是其中的逻辑，当然现在很多人都开始使用jquery了，大家也多注意。
原理性样例
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