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  • Javascript如何实现水印效果

    如图:

    image

    如何实现图中效果:

    1.在文本框中给出提示

    2.当点击输入时,提示消失

    3.当点击文本框,但未输入数据,失去焦点时仍给出提示.

    实现过程如下:

    1.一个span和一个文本框

    2.设置span的文本内容为提示内容

    3.设置文本框的的样式和事件.

    主要就是设置文本框的位置,设置绝对定位,定位在span的上面,然后设置文本框的背景颜色为transparent即可.

    具体代码如下:

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <title>无标题页</title>
        <style type="text/css">
            
            
            #txt
            {
            	position:absolute;
            	top:10px;
            	left:10px; 
            	background-color:Transparent; 
            	z-index:100;          
            }
            
            #txt2
            {
            	position:absolute;
            	top:35px;
            	left:10px;
            	background-color:Transparent;
            }
            
            .span1
            {
            	color:Silver;
            	left:10px;
            }
            
            .span2
            {
            	color:White;
            	left:10px;
            }
        </style>
        
    </head>
    <body style="margin:10px">
        <span class="span1" id='sp'>
            姓名:
        </span>
        <input type="text" id='txt' />
        <br />
        <span class="span1" id='sp2'>
            密码:
        </span>
        <input type="text" id='txt2' />
        <script type="text/javascript">
            document.getElementById("txt").onclick=function(){
                document.getElementById("sp").className="span2";
            };
            
            document.getElementById("txt2").onclick=function(){
                document.getElementById("sp2").className="span2";
            };
            
            document.getElementById("txt").onblur=function(){
                if(window.event.srcElement.value==''){
                    document.getElementById("sp").className="span1";
                }
            };
            
            document.getElementById("txt2").onblur=function(){
                if(window.event.srcElement.value==''){
                    document.getElementById("sp2").className="span1";
                }
            };
            
        </script>
    </body>
    </html>
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  • 原文地址:https://www.cnblogs.com/oneword/p/1619741.html
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