Escape Quote in C# for javascript consumption

Question

I have a ASP.Net web handler that returns results of a query in JSON format

public static String dt2JSON(DataTable dt)
{
    String s = \"{\\\"rows\\\":[\";
         


        

Answer 1

Here is an efficient and robust method that I found at http://www.west-wind.com/weblog/posts/114530.aspx

/// <summary>
/// Encodes a string to be represented as a string literal. The format
/// is essentially a JSON string.
/// 
/// The string returned includes outer quotes 
/// Example Output: "Hello \"Rick\"!\r\nRock on"
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public static string EncodeJsString(string s)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("\"");
    foreach (char c in s)
    {
        switch (c)
        {
            case '\"':
                sb.Append("\\\"");
                break;
            case '\\':
                sb.Append("\\\\");
                break;
            case '\b':
                sb.Append("\\b");
                break;
            case '\f':
                sb.Append("\\f");
                break;
            case '\n':
                sb.Append("\\n");
                break;
            case '\r':
                sb.Append("\\r");
                break;
            case '\t':
                sb.Append("\\t");
                break;
            default:
                int i = (int)c;
                if (i < 32 || i > 127)
                {
                    sb.AppendFormat("\\u{0:X04}", i);
                }
                else
                {
                    sb.Append(c);
                }
                break;
        }
    }
    sb.Append("\"");

    return sb.ToString();
}

Answer 2

I think you should rather look at the JavaScriptSerializer class. It's a lot more stable, and will correctly handle any kind of data or escape characters etc. Also, your code will look a lot cleaner.

In your case your class can look like this:

public static String dt2JSON(DataTable dt) {
    var rows = new List<Object>();
    foreach(DataRow row in dt.Rows)
    {
        var rowData = new Dictionary<string, object>();
        foreach(DataColumn col in dt.Columns)
            rowData[col.ColumnName] = row[col];
        rows.Add(rowData);
    }
    var js = new JavaScriptSerializer();
    return js.Serialize(new { rows = rows });
}

This method will return a correctly serialized json string... For example, sth like this:

{"rows":[{"id":1,"name":"hello"},{"id":2,"name":"bye"}]}

Have fun! :)

Answer 3

Works when i need send string from C# to html tag.

<buton onlick="alert('<< here >>')" />

HttpUtility.HtmlEncode

Answer 4

Here is a rework of @Bryan Legend's answer with Linq:

public static string EncodeJavaScriptString(string s)
    => string.Concat(s.Select(c => {
        switch (c)
        {
            case '\"': return "\\\"";
            case '\\': return "\\\\";
            case '\b': return "\\b";
            case '\f': return "\\f";
            case '\n': return "\\n";
            case '\r': return "\\r";
            case '\t': return "\\t";
            default: return (c < 32 || c > 127) && !char.IsLetterOrDigit(c) ? $"\\u{(int)c:X04}" : c.ToString();
        }}));

Try it Online!

changelog:

• Remove double quoting wrapping since I do it in the js
• Use expression body
• Use a cleaner switch
• Use Linq
• Add a check for Letter to allow é

Answer 5

Why don't you just do this:

string correctResponseText = wrongResponseText.Replace("\"", "\\\"");

Answer 6

Well, for starters you do not need quotes around the keys.

{rows:[,]} is valid.

and you could dt.Table.Columns[i].ToString().Replace("\","")

But if you want to retain the double quotes, single quote works the same way double quotes do in JS

Otherwise you could do

String.Format("{name: \"{0}\"}",Columns[i].ToString().Replace("\",""))