使用javascript和css来实现textbox水印效果

最新推荐文章于 2024-07-16 20:21:02 发布

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本文介绍如何使用JavaScript和CSS实现文本框水印效果，这种方法相较于AJAX更为节省资源。通过绑定文本框的'onfocus'和'onblur'事件，可以轻松地在聚焦和失焦时显示或隐藏提示信息。

Introduction

In this article, I will explain how watermark textbox using JavaScript and CSS is very useful and uses less resources compared to AJAX.

Overview

JavaScript is used to implement TextBox ‘onfocus’ and ‘onblur’ event and CSS is used to decorate TextBox.

Using the Code

a.Bind the onfucus event to remove watermark and the onblur event to decorate textbox as watermark.

<style type="text/css">
        .WaterMarkedTextBox
        {
            height: 16px;
            width: 168px;
            padding: 2px 2 2 2px;
            border: 1px solid #BEBEBE;
            background-color: #F0F8FF;
            color: gray;
            font-size: 8pt;
            text-align: center;
        }
        .WaterMarkedTextBoxPSW
        {
            background-position: center;
            height: 16px;
            width: 168px;
            padding: 2px 2 2 2px;
            border: 1px solid #BEBEBE;
            background-color: #F0F8FF;
            color: white;
            vertical-align: middle;
            text-align: right;
            background-image: url(Images/psw_wMark.png);
            background-repeat: no-repeat;
        }
        .NormalTextBox
        {
            height: 16px;
            width: 168px;
        }
    </style>

 <script language="javascript" type="text/javascript">
        function Focus(objname, waterMarkText) {
            obj = document.getElementById(objname);
            if (obj.value == waterMarkText) {
                obj.value = "";
                obj.className = "NormalTextBox";
                if (obj.value == "User ID" || obj.value == "" || obj.value == null) {
                    obj.style.color = "black";
                }
            }
        }
        function Blur(objname, waterMarkText) {
            obj = document.getElementById(objname);
            if (obj.value == "") {
                obj.value = waterMarkText;
                if (objname != "txtPwd") {
                    obj.className = "WaterMarkedTextBox";
                }
                else {
                    obj.className = "WaterMarkedTextBoxPSW";
                }
            }
            else {
                obj.className = "NormalTextBox";
            }

            if (obj.value == "User ID" || obj.value == "" || obj.value == null) {
                obj.style.color = "gray";
            }
        }
    </script>

<body>
    <form id="form1" runat="server">
    <div>
        <h3>
            Watermark Textbox using JavaScript and CSS</h3>
    </div>
    <table>
        <tr>
            <td>
                User Id
            </td>
            <td>
                <asp:TextBox ID="txtUserId" runat="server" 
		onfocus="Focus(this.id,'User ID')"
                    onblur="Blur(this.id,'User ID')" 
		    Width="126px" CssClass="WaterMarkedTextBox">User ID</asp:TextBox>
            </td>
        </tr>
        <tr>
            <td>
                Password
            </td>
            <td>
                <asp:TextBox ID="txtPwd" TextMode="Password" 
		runat="server" onfocus="Focus(this.id,'')"
                    onblur="Blur(this.id,'')" Width="126px" 
			CssClass="WaterMarkedTextBoxPSW" />
            </td>
        </tr>
        <tr>
            <td>
            </td>
            <td>
                <asp:Button ID="Button1" runat="server" Text="Submit" />
            </td>
        </tr>
    </table>
    </form>
</body>