This is a gotcha which caught me out and after banging my head against my desk to 10 minutes was easily solved by reading the documentation. I was trying to use StringBuilder.AppendFormat to build up a JavaScript function and kept getting hit with a FormatException when trying to do this:
sb.AppendFormat("function {0}(args) { return false; }", someVariable);
The problem, of course, is that you can’t use the characters { or } inside a format string for String.Format() as they are special characters used to identify variables, as I have done in the example with the use of {0}.
The solution is actually fairly straightforward but not immediately obvious. My first thought was to escape the special characters using the standard “\” , for example:
sb.AppendFormat("function {0}(args) \{ return false; \}", someVariable);
But that code generated the same FormatException. After a little while I gave up and read the documentation (remember kids, always RTFM!) for the answer. The code I wanted was:
sb.AppendFormat("function {0}(args) {{ return false; }}", someVariable);
Instead of using “\” as an escape character, you double up the special characters {{ or }}. Easy. When you know how.
