.NET Framework Regex 的行為與 JavaScript 的行為有所不同 ?? @ 慢步在雲端..

Problem:

之前在專案中, 有測到一個疑似一個 .NET Framework Regex 的 bug?

例如使用 PATTERN = “\w”

\w表示任何一個字元與數字以及 '_' ，意同 [a-zA-Z0-9_]

輸入全形英數字及中文字可以通過在 Server side 的 Regular expression 檢查

但相同的 pattern 在 Javascript 的 Regular expression 是不會過的

最近找到答案了…

Root Cause:

Server side RegExp uses a different regular expression engine than JavaScript.

Solution:

You can get compatible behavior by using a RegexOptions.EcmaScript with your Regex.

Regex regexp = new Regex("\\w", RegexOptions.ECMAScript);

For more information:

RegexOptions 列舉型別

http://msdn.microsoft.com/zh-tw/library/system.text.regularexpressions.regexoptions.aspx

ECMAScript vs. Canonical Matching Behavior

http://msdn.microsoft.com/en-us/library/04ses44d(VS.71).aspx

Sample:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="RegExpApp._Default" %>
<%@ Import Namespace="System" %>
<%@ Import Namespace="System.Text.RegularExpressions" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    <script language="javascript" type="text/javascript">
    function testRegExp()
    {
        var email = document.getElementById("<%=txtEmail.ClientID %>").value;
        var regexp = new RegExp("\\w");
        if (email.match(regexp)) {
                alert("Successful match");
        } else {
            alert("No match");
        }
    }
    </script>
    
    
    <script runat="server">
        protected void btnNETRegExp_Click(object sender, EventArgs e)
        {
            Regex regexp;

            if (chkECMAScript.Checked)
            {
                regexp = new Regex("\\w", RegexOptions.ECMAScript);
            }
            else
            {
                regexp = new Regex("\\w");
            }
            
            if(regexp.IsMatch(txtEmail.Text))
            {
                Response.Write("Successful match");
            }
            else{
                Response.Write("No match");
            }
            
        }
        
    
    </script>
    
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:TextBox ID="txtEmail" runat="server"></asp:TextBox>
        <br />
        <br />
        <asp:Button ID="btnNETRegExp" runat="server" Text="NET RegExp" OnClick="btnNETRegExp_Click" />
        &nbsp;&nbsp;&nbsp;
        <asp:CheckBox ID="chkECMAScript" runat="server" />
        <br />
        <br />
        <input id="btnJSRegExp" type="button" value="JavaScript RegExp" onclick="testRegExp();" /></div>
    </form>
</body>
</html>