Table of Contents

Topic 1: Detecting user input: " >Topic 1: Detecting user input:

" > Topic 2: Setting the default style of the text box:

" >Topic 3: : Design a table style to realize the function of selecting all and inverting the selection

Home

Web Front-end

JS Tutorial

[js]: Detect user input, text box default style setting, design table style to achieve select all and invert selection

php是最好的语言

Aug 07, 2018 am 10:27 AM

Topic 1: Detecting user input:

##Topic requirements:

Write a user registration page

Check whether the username is less than 6 characters and whether the password is more than 8 characters. If the requirements are not met, highlight the text box;

The code is as follows:

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>用户注册页面</title>
	<style>
		.bg {background-color: red; }
	</style>
</head>

<body>
	<!-----id适用于js中的--->
	<input type="text" name="name" id="name" /><br>
	<input type="text" name="pwd" id="pwd" /><br>
	<input type="submit" value="注册" id="submit" />
	
	<script>
//	编写一个用户注册页面
//	检测用户名是否是6位以下，密码是否是8位以上，如果不满足要求高亮显示文本框 ；
		var nameText = document.getElementById(&#39;name&#39;);
		var pwdText = document.getElementById(&#39;pwd&#39;);
		var submit = document.getElementById(&#39;submit&#39;);
		//给submit按钮注册事件
		submit.onclick = function () {
			if(nameText.value.length < 6 && nameText.value.length > 0) {
				nameText.className = &#39;&#39;;
			} else {
				nameText.className = &#39;bg&#39;;
			}
			
			if(pwdText.value.length > 8 && pwdText.value.length < 16) {
				pwdText.className = &#39;&#39;;
			} else {
				pwdText.className = &#39;bg&#39;;
			}
			//取消submit的默认行为的执行   if里面不需要这句了  如果加了肯能会影响后续代码的执行
			return false;
		}
	
	</script>
</body>
</html>

Copy after login

Topic 2: Setting the default style of the text box:

[js]: Detect user input, text box default style setting, design table style to achieve select all and invert selection

#This sentence can set the default value of the text box;

The effect is:

[js]: Detect user input, text box default style setting, design table style to achieve select all and invert selection

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>设置文本框中的默认样式</title>
	<style>
		.bg {color: gray; }
		
	</style>
</head>

<body>
	<input type="text" id="textSearch" class="bg" value="请输入关键字" >
	<input type="button" value="搜索">
	
	<script>
		//注册事件
		//如果文本框获得焦点 当内容是请输入关键字 清空内容  文字颜色恢复默认的黑色
		var textSearch = document.getElementById(&#39;textSearch&#39;);
		textSearch.onfocus = function () {
			if(textSearch.value === &#39;请输入关键字&#39;) {
				this.value = &#39;&#39;;
				//把this的属性恢复为默认值   这里作用是把文字颜色变为黑色
				this.className = &#39;&#39;;
			}
		}
		// 当失去焦点的时候onblur。如果文本框中的内容为空  设置文本框中内容为 请输入关键字 设置字体颜色为gray
		textSearch.onblur = function () {
			// if (textSearch.value === &#39;&#39;) {}
			// 这一句不太好的  这个要是用户第一个输入的是空格的话那么就会误判  我们可以用它的长度来判断
			if (textSearch.value.length === 0) {
				this.className = &#39;bg&#39;;
				this.value = &#39;请输入关键字&#39;;
			}
		}

		
	</script>
</body>
</html>

Copy after login

Topic 3: : Design a table style to realize the function of selecting all and inverting the selection

Function to be realized:

1 When clicking the select all button (parent's checkbox), keep the selected state of the child's checkbox consistent with the parent's checkbox

2 Register click events for all child's checkboxes, Click the child's checkbox. If one of the child's checkboxes is not selected, the parent's checkbox is also not selected

3 Inverse selection

Code example:

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>全选反选</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        .wrap {
            width: 300px;
            margin: 100px auto 0;
        }

        table {
            border-collapse: collapse;
            border-spacing: 0;
            border: 1px solid #c0c0c0;
            width: 300px;
        }

        th,
        td {
            border: 1px solid #d0d0d0;
            color: #404060;
            padding: 10px;
        }

        th {
            background-color: #09c;
            font: bold 16px "微软雅黑";
            color: #fff;
        }

        td {
            font: 14px "微软雅黑";
        }

        tbody tr {
            background-color: #f0f0f0;
        }

        tbody tr:hover {
            cursor: pointer;
            background-color: #fafafa;
        }
    </style>
</head>
<body>
  <p class="wrap">
      <table>
          <thead>
            <tr>
                <th>
                    <input type="checkbox" id="father" />
                </th>
                <th>商品</th>
                <th>价钱</th>
            </tr>
          </thead>
          <tbody id="son">
            <tr>
                <td>
                    <input type="checkbox" />
                </td>
                <td>iPhone8</td>
                <td>8000</td>
            </tr>
            <tr>
                <td>
                    <input type="checkbox" />
                </td>
                <td>iPad Pro</td>
                <td>5000</td>
            </tr>
            <tr>
                <td>
                    <input type="checkbox" />
                </td>
                <td>iPad Air</td>
                <td>2000</td>
            </tr>
            <tr>
                <td>
                    <input type="checkbox" />
                </td>
                <td>Apple Watch</td>
                <td>2000</td>
            </tr>

          </tbody>
      </table>
      <input type="button" value="  反 选  " id="btn">
	  <script>
	  	  // 1 点击全选按钮(父的checkbox)的时候，让子的checkbox的选中状态跟父的checkbox保持一致
		  //1.1  给父级的check注册事件
		  //获取父级checkbox 
		  var father = document.getElementById(&#39;father&#39;);
		  //获取所有的子级checkbox
		  //注意这一句用选择器的获得元素的写法
		  var sons = document.querySelectorAll(&#39;#son input[type=checkbox]&#39;);
		  var len = sons.length;
		  father.onclick = function () {
			 //1.2遍历这个容器中的所有元素   让所有的子级checkbox的状态都等于父级的状态
			  for(var i = 0;i < len; i++) {
				  //注意这一句话是核心   让子级的checkbox的状态等于父级
				  sons[i].checked = this.checked;
			  }
		  }
		  
		  
		  
		  // 2 给所有的子的checkbox注册点击事件，点击子的checkbox 如果有一个子的checkbox没有选中，父的checkbox也不选中
		  // 2.1 给所有的子的checkbox注册点击事件
		  // 核心代码封装成方法  便于使用
		  function step2 () {
			  //2.2 只要子级有一个是false那么父级也就是false
			  //2.2 定义一个变量用于父级的状态   这个fatherIsTrue必须在点击事件这里面  father的赋值也是  因为每个点击事件需要判断所有的子级的状态  在外面的话是实现不了的
		 	  var fatherIsTrue = true;
			  for (var j = 0; j < len; j++) {
				  if (!sons[j].checked) {
					  fatherIsTrue = false;
					  break;
					  }
			  }
				  father.checked = fatherIsTrue;
		  }
		  
		  for(var i = 0;i < len; i++) {
			  sons[i].onclick = function () {
				  step2();
			  }
		  }
		  
		  
		  //3 反选
		  // 给反选按钮注册一个事件
		  var btn = document.getElementById(&#39;btn&#39;);
		  btn.onclick = function () {
			  for(var i = 0; i < len; i++) {
				  sons[i].checked = !sons[i].checked;
			  }
			  //写到这里我门会有一个问题就是反选不能控制父级  但是呢我们的第二步已经完成这个问题了  所以我们把第二步
			  //的核心代码分装成一个方法  直接调用即可  直接粘贴复制过来不太好
			  step2();
		  }
	  </script>
  </p>
</body>
</html>

Copy after login

Web page example:

[js]: Detect user input, text box default style setting, design table style to achieve select all and invert selection

Note: This sentence is the core. Let the status of the child's checkbox be equal to the parent's sons [i].checked = this.checked;

Related recommendations:

How to select and invert all js checkboxes

js Implementation code for setting the style of the selected row

The above is the detailed content of [js]: Detect user input, text box default style setting, design table style to achieve select all and invert selection. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress images for free

Clothoff.io

AI clothes remover

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Roblox: Grow A Garden - Complete Mutation Guide

4 weeks ago By DDD

Roblox: Bubble Gum Simulator Infinity - How To Get And Use Royal Keys

1 months ago By 尊渡假赌尊渡假赌尊渡假赌

Nordhold: Fusion System, Explained

1 months ago By 尊渡假赌尊渡假赌尊渡假赌

Mandragora: Whispers Of The Witch Tree - How To Unlock The Grappling Hook

4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌

Clair Obscur: Expedition 33 UE-Sandfall Game Crash? 3 Ways!

2 weeks ago By DDD

Hot Tools

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial

1677

CakePHP Tutorial

1431

Laravel Tutorial

1334

PHP Tutorial

1279

C# Tutorial

1257

Related knowledge

Python vs. JavaScript: The Learning Curve and Ease of Use Apr 16, 2025 am 12:12 AM

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

JavaScript and the Web: Core Functionality and Use Cases Apr 18, 2025 am 12:19 AM

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

JavaScript in Action: Real-World Examples and Projects Apr 19, 2025 am 12:13 AM

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

Understanding the JavaScript Engine: Implementation Details Apr 17, 2025 am 12:05 AM

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python vs. JavaScript: Development Environments and Tools Apr 26, 2025 am 12:09 AM

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

The Role of C/C in JavaScript Interpreters and Compilers Apr 20, 2025 am 12:01 AM

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

From Websites to Apps: The Diverse Applications of JavaScript Apr 22, 2025 am 12:02 AM

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python vs. JavaScript: Use Cases and Applications Compared Apr 21, 2025 am 12:01 AM

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

See all articles