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>

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>

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>

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

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

Replace String Characters in JavaScriptMar 11, 2025 am 12:07 AM

Detailed explanation of JavaScript string replacement method and FAQ This article will explore two ways to replace string characters in JavaScript: internal JavaScript code and internal HTML for web pages. Replace string inside JavaScript code The most direct way is to use the replace() method: str = str.replace("find","replace"); This method replaces only the first match. To replace all matches, use a regular expression and add the global flag g: str = str.replace(/fi

Build Your Own AJAX Web ApplicationsMar 09, 2025 am 12:11 AM

So here you are, ready to learn all about this thing called AJAX. But, what exactly is it? The term AJAX refers to a loose grouping of technologies that are used to create dynamic, interactive web content. The term AJAX, originally coined by Jesse J

10 jQuery Fun and Games PluginsMar 08, 2025 am 12:42 AM

10 fun jQuery game plugins to make your website more attractive and enhance user stickiness! While Flash is still the best software for developing casual web games, jQuery can also create surprising effects, and while not comparable to pure action Flash games, in some cases you can also have unexpected fun in your browser. jQuery tic toe game The "Hello world" of game programming now has a jQuery version. Source code jQuery Crazy Word Composition Game This is a fill-in-the-blank game, and it can produce some weird results due to not knowing the context of the word. Source code jQuery mine sweeping game

How do I create and publish my own JavaScript libraries?Mar 18, 2025 pm 03:12 PM

Article discusses creating, publishing, and maintaining JavaScript libraries, focusing on planning, development, testing, documentation, and promotion strategies.

jQuery Parallax Tutorial - Animated Header BackgroundMar 08, 2025 am 12:39 AM

This tutorial demonstrates how to create a captivating parallax background effect using jQuery. We'll build a header banner with layered images that create a stunning visual depth. The updated plugin works with jQuery 1.6.4 and later. Download the

How do I optimize JavaScript code for performance in the browser?Mar 18, 2025 pm 03:14 PM

The article discusses strategies for optimizing JavaScript performance in browsers, focusing on reducing execution time and minimizing impact on page load speed.

Getting Started With Matter.js: IntroductionMar 08, 2025 am 12:53 AM

Matter.js is a 2D rigid body physics engine written in JavaScript. This library can help you easily simulate 2D physics in your browser. It provides many features, such as the ability to create rigid bodies and assign physical properties such as mass, area, or density. You can also simulate different types of collisions and forces, such as gravity friction. Matter.js supports all mainstream browsers. Additionally, it is suitable for mobile devices as it detects touches and is responsive. All of these features make it worth your time to learn how to use the engine, as this makes it easy to create a physics-based 2D game or simulation. In this tutorial, I will cover the basics of this library, including its installation and usage, and provide a

Auto Refresh Div Content Using jQuery and AJAXMar 08, 2025 am 12:58 AM

This article demonstrates how to automatically refresh a div's content every 5 seconds using jQuery and AJAX. The example fetches and displays the latest blog posts from an RSS feed, along with the last refresh timestamp. A loading image is optiona

See all articles