Javascript small case: imitating Taobao search box user input-JS Tutorial-php.cn

Javascript small case: imitating Taobao search box user input

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Release： 2017-09-06 10:01:38

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Taobao is an online shopping platform we often use. Open the Taobao homepage and find the search box on the Taobao homepage, as shown below:

Javascript small case: imitating Taobao search box user input

As you can see, when the page is opened, you can see the gray font "Girls' High Heels" in the search box, as well as a blinking cursor. When the user clicks to enter, the gray text disappears. When the user clears all the contents of the text box, the gray text is automatically restored.

Next, this small case will introduce how to achieve this effect, that is, user input events.

The events that determine user input include oninput and onpropertychange. Of course, you can probably imagine that due to browser compatibility issues, they appear in different situations. Normal browsers support oninput, while IE6, IE7, and IE8 support onpropertychange.

In order to save time, I will no longer imitate Taobao CSS styles.

Code and analysis:

<!DOCTYPE html><html lang="en"><head>
    <meta charset="UTF-8">
    <title>判断用户输入事件第2遍oninput 和onpropertychange 的用法</title></head>
 <style>
        .search {            
        width:300px;            
        height: 30px;            
        margin: 100px auto;            
        position: relative;        
        }
        .search input {            
        width:200px;            
        height:25px;        
        }
        .search label {            
        font-size: 12px;            
        color:#ccc;            
        position: absolute;            
        top:8px;            
        left:10px;            
        cursor: text;        
        }
    </style>
    <script type="text/javascript">
    业务逻辑分析：//           
    1.内容为空时，光标和默认字显示在搜索框。自动获取焦点//           
    2.当输入内容时，默认字消失。用oninput事件

        window.onload = function () {
            function $(id){ return document.getElementById(id);}
            $("txt").focus();//自动获取光标方法
            $("txt").oninput = $("txt").onpropertychange = function () {
            //oninput 大部分浏览器支持  检测用户表单输入内容
            //onpropertychange  ie678  检测用户表单输入内容
                if ( this.value == ""){                    
                // 首先判断文本框里的值是否为空。注意用双等号！
                    $("message").style.display = "block";
                } else {
                    $("message").style.display = "none";
                }
            }
        }    </script>  <body><p class="search">
    <input type="text" id="txt">
    <label for="txt" id="message">仿淘宝搜索框</label>
    <!-- 注意label 中for属性 值指向 input 的id值 ，意思是把label标签和input表单相关联。
    label 元素不会向用户呈现任何特殊效果。当用户在label元素内点击文本， 浏览器就会自动将焦点转到和标签相关联的表单控件上。 --></p></body></html>

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Effect:

Javascript small case: imitating Taobao search box user input

No one can reach a thousand miles without taking small steps. A big website is made up of small ones. To build the functions, the emphasis is on actual combat and typing the code. I type a case three times until I am familiar with it. I believe that over time, I will become a great expert. Encourage yourself and encourage each other. Thanks!

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