string.Format throws System.Format exception on HTML + javascript

Question

I'm running string.Format on a readonly string that contains a bit of HTML + javascript but I get a System.FormatException instead.

This is my format string:

<script type="text/javascript">
    function {0}_showHideFieldWindow() {
        if ({0}.IsCustomizationWindowVisible()) {
            {0}.HideCustomizationWindow();
        } else {
            {0}.ShowCustomizationWindow();
        }
    }
</script>

All i'm doing is passing in the object name. Like this:

string.Format(javascript, "grid");

Answer 1

Since you have curly braces in the string you need to escape them by doubling them up ({{ and }}) to prevent the formatter from thinking they are tokens.

Your string initialization should look something like this:

String javascript = @"<script type=""text/javascript"">
         function {0}_showHideFieldWindow() {{
      if ({0}.IsCustomizationWindowVisible()) {{
          {0}.HideCustomizationWindow();
      }} else {{
          {0}.ShowCustomizationWindow();
      }}
     }}
    </script>";

Answer 2

String.Format needs the extra brackets to be escaped. You might be better off doing something like this, which might be more readable than escaping each bracket if you don't need all of String.Format's functionality:

mystring.Replace("{0}","grid");