内部JS:javascript
定义<script>,标签体内容就是js代码
外部JS:html
定义<script>,经过src属性引入外部的js文件
1. <script>能够定义在html页面的任何地方。可是定义的位置会影响执行顺序。 2. <script>能够定义多个。
算数运算符java
+,-,*,/,% ...正则表达式
赋值运算符数组
= += -+....浏览器
比较运算符app
< >= <= == ===(全等于)dom
三元运算符
? : 表达式
var a = 3;
var b = 4;ecmascript
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>99乘法表</title> <style> td{ border: 1px solid; } </style> <script> document.write("<table align='center'>"); //1.完成基本的for循环嵌套,展现乘法表 for (var i = 1; i <= 9 ; i++) { document.write("<tr>"); for (var j = 1; j <=i ; j++) { document.write("<td>"); //输出 1 * 1 = 1 document.write(i + " * " + j + " = " + ( i*j) +" "); document.write("</td>"); } /*//输出换行 document.write("<br>");*/ document.write("</tr>"); } //2.完成表格嵌套 document.write("</table>"); </script> </head> <body> </body> </html>
与定时器有关的方式
setTimeout() 在指定的毫秒数后调用函数或计算表达式。
* 参数:
1. js代码(字符串)或者方法对象(fun)
2. 毫秒值
* 返回值:惟一标识,用于取消定时器
clearTimeout() 取消由 setTimeout() 方法设置的 timeout。函数
setInterval() 按照指定的周期(以毫秒计)来调用函数或计算表达式。
clearInterval() 取消由 setInterval() 设置的 timeout。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>自动跳转</title> <style> p { text-align: center; } #time { color: red; } </style> </head> <body> <p> <span id="time">5</span> 秒以后,自动跳转到首页... </p> <script> var time = document.getElementById("time"); var second = 5; function show() { second--; if (second <= 0) { location.href="https://www.baidu.com"; } time.innerHTML = second + ""; } setInterval(show, 1000); </script> </body> </html>
<body> <!-- onclick在属性值里耦合度高 --> <img id="light" src="img/off.gif" onclick="fun();"> <img id="light2" src="img/off.gif"> <script> function fun(){ alert('我被点了'); alert('我又被点了'); } function fun2(){ alert('咋老点我?'); } <!-- 这样比较好 --> //1.获取light2对象 var light2 = document.getElementById("light2"); //2.绑定事件 light2.onclick = fun2; </script> </body>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>电灯开关</title> </head> <body> <img id="light" src="img/off.gif"> <script> /* 分析: 1.获取图片对象 2.绑定单击事件 3.每次点击切换图片 * 规则: * 若是灯是开的 on,切换图片为 off * 若是灯是关的 off,切换图片为 on * 使用标记flag来完成 */ //1.获取图片对象 var light = document.getElementById("light"); var flag = false;//表明灯是灭的。 off图片 //2.绑定单击事件 light.onclick = function(){ if(flag){//判断若是灯是开的,则灭掉 light.src = "img/off.gif"; flag = false; }else{ //若是灯是灭的,则打开 light.src = "img/on.gif"; flag = true; } } </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>表格全选</title> <style> table{ border: 1px solid; width: 500px; margin-left: 30%; } td,th{ text-align: center; border: 1px solid; } div{ margin-top: 10px; margin-left: 30%; } .out{ background-color: white; } .over{ background-color: pink; } </style> <script> /* 分析: 1.全选: * 获取全部的checkbox * 遍历cb,设置每个cb的状态为选中 checked */ //1.在页面加载完后绑定事件 window.onload = function(){ //2.给全选按钮绑定单击事件 document.getElementById("selectAll").onclick = function(){ //全选 //1.获取全部的checkbox var cbs = document.getElementsByName("cb"); //2.遍历 for (var i = 0; i < cbs.length; i++) { //3.设置每个cb的状态为选中 checked cbs[i].checked = true; } } document.getElementById("unSelectAll").onclick = function(){ //全不选 //1.获取全部的checkbox var cbs = document.getElementsByName("cb"); //2.遍历 for (var i = 0; i < cbs.length; i++) { //3.设置每个cb的状态为未选中 checked cbs[i].checked = false; } } document.getElementById("selectRev").onclick = function(){ //反选 //1.获取全部的checkbox var cbs = document.getElementsByName("cb"); //2.遍历 for (var i = 0; i < cbs.length; i++) { //3.设置每个cb的状态为相反 cbs[i].checked = !cbs[i].checked; } } document.getElementById("firstCb").onclick = function(){ //第一个cb点击 //1.获取全部的checkbox var cbs = document.getElementsByName("cb"); //获取第一个cb //2.遍历 for (var i = 0; i < cbs.length; i++) { //3.设置每个cb的状态和第一个cb的状态同样 cbs[i].checked = this.checked; } } //给全部tr绑定鼠标移到元素之上和移出元素事件 var trs = document.getElementsByTagName("tr"); //2.遍历 for (var i = 0; i < trs.length; i++) { //移到元素之上 trs[i].onmouseover = function(){ this.className = "over"; } //移出元素 trs[i].onmouseout = function(){ this.className = "out"; } } } </script> </head> <body> <table> <caption>学生信息表</caption> <tr> <th><input type="checkbox" name="cb" id="firstCb"></th> <th>编号</th> <th>姓名</th> <th>性别</th> <th>操做</th> </tr> <tr> <td><input type="checkbox" name="cb" ></td> <td>1</td> <td>令狐冲</td> <td>男</td> <td><a href="javascript:void(0);">删除</a></td> </tr> <tr> <td><input type="checkbox" name="cb" ></td> <td>2</td> <td>任我行</td> <td>男</td> <td><a href="javascript:void(0);">删除</a></td> </tr> <tr> <td><input type="checkbox" name="cb" ></td> <td>3</td> <td>岳不群</td> <td>?</td> <td><a href="javascript:void(0);">删除</a></td> </tr> </table> <div> <input type="button" id="selectAll" value="全选"> <input type="button" id="unSelectAll" value="全不选"> <input type="button" id="selectRev" value="反选"> </div> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>注册页面</title> <style> *{ margin: 0px; padding: 0px; box-sizing: border-box; } body{ background: url("img/register_bg.png") no-repeat center; padding-top: 25px; } .rg_layout{ width: 900px; height: 500px; border: 8px solid #EEEEEE; background-color: white; /*让div水平居中*/ margin: auto; } .rg_left{ /*border: 1px solid red;*/ float: left; margin: 15px; } .rg_left > p:first-child{ color:#FFD026; font-size: 20px; } .rg_left > p:last-child{ color:#A6A6A6; font-size: 20px; } .rg_center{ float: left; /* border: 1px solid red;*/ } .rg_right{ /*border: 1px solid red;*/ float: right; margin: 15px; } .rg_right > p:first-child{ font-size: 15px; } .rg_right p a { color:pink; } .td_left{ width: 100px; text-align: right; height: 45px; } .td_right{ padding-left: 50px ; } #username,#password,#email,#name,#tel,#birthday,#checkcode{ width: 251px; height: 32px; border: 1px solid #A6A6A6 ; /*设置边框圆角*/ border-radius: 5px; padding-left: 10px; } #checkcode{ width: 110px; } #img_check{ height: 32px; vertical-align: middle; } #btn_sub{ width: 150px; height: 40px; background-color: #FFD026; border: 1px solid #FFD026 ; } .error{ color:red; } #td_sub{ padding-left: 150px; } </style> <script> /* 分析: 1.给表单绑定onsubmit事件。监听器中判断每个方法校验的结果。 若是都为true,则监听器方法返回true 若是有一个为false,则监听器方法返回false 2.定义一些方法分别校验各个表单项。 3.给各个表单项绑定onblur事件。 */ window.onload = function(){ //1.给表单绑定onsubmit事件 document.getElementById("form").onsubmit = function(){ //调用用户校验方法 chekUsername(); //调用密码校验方法 chekPassword(); //return checkUsername() && checkPassword(); return checkUsername() && checkPassword(); } //给用户名和密码框分别绑定离焦事件 document.getElementById("username").onblur = checkUsername; document.getElementById("password").onblur = checkPassword; } //校验用户名 function checkUsername(){ //1.获取用户名的值 var username = document.getElementById("username").value; //2.定义正则表达式 var reg_username = /^\w{6,12}$/; //3.判断值是否符合正则的规则 var flag = reg_username.test(username); //4.提示信息 var s_username = document.getElementById("s_username"); if(flag){ //提示绿色对勾 s_username.innerHTML = "<img width='35' height='25' src='img/gou.png'/>"; }else{ //提示红色用户名有误 s_username.innerHTML = "用户名格式有误"; } return flag; } //校验密码 function checkPassword(){ //1.获取用户名的值 var password = document.getElementById("password").value; //2.定义正则表达式 var reg_password = /^\w{6,12}$/; //3.判断值是否符合正则的规则 var flag = reg_password.test(password); //4.提示信息 var s_password = document.getElementById("s_password"); if(flag){ //提示绿色对勾 s_password.innerHTML = "<img width='35' height='25' src='img/gou.png'/>"; }else{ //提示红色用户名有误 s_password.innerHTML = "密码格式有误"; } return flag; } </script> </head> <body> <div class="rg_layout"> <div class="rg_left"> <p>新用户注册</p> <p>USER REGISTER</p> </div> <div class="rg_center"> <div class="rg_form"> <!--定义表单 form--> <form action="#" id="form" method="get"> <table> <tr> <td class="td_left"><label for="username">用户名</label></td> <td class="td_right"> <input type="text" name="username" id="username" placeholder="请输入用户名"> <span id="s_username" class="error"></span> </td> </tr> <tr> <td class="td_left"><label for="password">密码</label></td> <td class="td_right"> <input type="password" name="password" id="password" placeholder="请输入密码"> <span id="s_password" class="error"></span> </td> </tr> <tr> <td class="td_left"><label for="email">Email</label></td> <td class="td_right"><input type="email" name="email" id="email" placeholder="请输入邮箱"></td> </tr> <tr> <td class="td_left"><label for="name">姓名</label></td> <td class="td_right"><input type="text" name="name" id="name" placeholder="请输入姓名"></td> </tr> <tr> <td class="td_left"><label for="tel">手机号</label></td> <td class="td_right"><input type="text" name="tel" id="tel" placeholder="请输入手机号"></td> </tr> <tr> <td class="td_left"><label>性别</label></td> <td class="td_right"> <input type="radio" name="gender" value="male" checked> 男 <input type="radio" name="gender" value="female"> 女 </td> </tr> <tr> <td class="td_left"><label for="birthday">出生日期</label></td> <td class="td_right"><input type="date" name="birthday" id="birthday" placeholder="请输入出生日期"></td> </tr> <tr> <td class="td_left"><label for="checkcode" >验证码</label></td> <td class="td_right"><input type="text" name="checkcode" id="checkcode" placeholder="请输入验证码"> <img id="img_check" src="img/verify_code.jpg"> </td> </tr> <tr> <td colspan="2" id="td_sub"><input type="submit" id="btn_sub" value="注册"></td> </tr> </table> </form> </div> </div> <div class="rg_right"> <p>已有帐号?<a href="#">当即登陆</a></p> </div> </div> </body> </html>