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Basic elements of html form

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Release： 2018-06-29 10:22:11

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Basic elements of forms

1. Let’s first take a look at what a form is? Almost every website will have one

2. The most direct impression of a form is that it has some input boxes. There are also some buttons

3. These input boxes can accept data input by users, and the buttons can submit user data

4. The form elements are composed of a set of tags

There are many ways to submit forms, the most important are two:

1.get method: This is also the default method. All form data submitted by the user is on the url address

The advantage is that it is easy to collect and call repeatedly, but the disadvantage is that it is unsafe and the amount of data is limited

2. Post method: data is submitted through the request header, the URL address bar cannot be seen, it is very safe, and the length is not limited

The get method is very suitable for transmitting insensitive and short-length data

The post method is very suitable for transmitting important data and data of uncertain length

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>3-1表单的基本元素</title>
</head>
<body>
<form action="demo.php" method="get">
<!-- <form action="demo.php" method="post"> -->
<!-- 最重要的输入控件标签是<input>,它有很多类型,是由type属性来指定的 -->
<!-- 1.文本框: 最常见,可以输入文本,常用来输入用户名帐号等 -->
<!-- 因为input是一个内联元素,多个input会在一行显示,所以后面加一个换行标签 -->
<!-- name是输入控件的名称,一定要设置,因为PHP要用它当变量名来获取表单的数据
value保存的是用户输入的数据,通常保持为空即可 -->
姓名:<input type="text" name="name" value=""> <br>
<!-- 2.密码框: type="password",和文本是一样的,只是用户输入的内容以星号代替 -->
密码:<input type="password" name="password" value=""> <br>
<!-- 3.单选框:顾名思义就是每次只能选择一项,例如性别,付款方式等只能选择一个且选项较少的情况 -->
<!-- 单选按钮的name值必须全部一样,才能确保仅返回一个选择 -->
<!-- 可以设置默认选择荐:checked:它是布尔属性,不需要赋值,如果要给值就是它自己 -->
性别:<input type="radio" name="sex" value="male">男
<input type="radio" name="sex" value="woman">女
<input type="radio" name="sex" value="secret" checked>保密
<br>
<!-- 4.复选框:就是一次可以选择多个数据提交,返回值是一个数组,name属性要加[],确保返回数组 -->
爱好:<input type="checkbox" name="hobby[]" value="movie">看电影
   <input type="checkbox" name="hobby[]" value="game" checked>打游戏
   <input type="checkbox" name="hobby[]" value="cook">做饭
   <input type="checkbox" name="hobby[]" value="wash">洗衣服
   <br>
<!-- 5:下拉列表框:点击后会出一个下拉列表,用户可以选择一个或多个选项 -->
<!-- 下拉列表使用的是select标签,名值对name和value分在二个标签中 -->
<!-- name写在父标签select中,value写在option子标签中,可以用selected属性设置默认值 -->
级别: <select name="level">
<option value="0">纯洁的小白</option>
<option value="1">有点污啦</option>
<option value="2" selected>目空一切</option>
<option value="3">宇宙无敌小霸王</option>
</select>
<br>
<!-- 6.文件上传域:accept属性设置允许上传的文件类型,不过这个很少用,应该在服务器进行判断 -->
头像:<input type="file" name="photo" accept="image/*"> <br>
<!-- 特殊的隐藏域:type="hidden",为什么要用隐藏域呢?
1.有一些数据是自动生成的,不需要用户输入:例如注册时间
2.有一些数据用户是不知道的,例如,用户id
3.后端通过表单向一些页面传数据时使用的主键或关键字 -->
<!-- 在页面看不到隐藏域的东西,但是提交后可以在后台看到通过隐藏域传递过来的数据 -->
<input type="hidden" name="user_id" value="10">
文本域:<textarea name="comment" rows="5" cols="30"></textarea><br>
<!-- 7.提交按钮:type="submit",type="button"是普通按钮,失去提交功能 -->
<input type="submit" name="submit" value="提交">
<input type="button" name="button" value="提交">
<!-- type="reset"可以重置用户数据,恢复到最初状态 -->
<input type="reset" name="reset" value="重置">
<!-- 8.提交图像按钮: type="image",默认就是提交功能,与submit功能是一样的 -->
<input type="image" name="submit" src="../images/submit.jpg" width="30">
</form>
</body>
</html>

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