Getting a Strace of Thrown Exceptions

While JavaScript allows for exceptions to be raised, obtaining a stack trace for a custom exception can be challenging. This article explores various methods to retrieve stack traces specifically for user-defined exceptions.

The stack property of an Error object provides a simple solution. By creating a new Error object and accessing its stack property, you can capture a trace:

function stackTrace() {
    var err = new Error();
    return err.stack;
}

This approach generates a stack trace similar to:

DBX.Utils.stackTrace@http://localhost:49573/assets/js/scripts.js:44
DBX.Console.Debug@http://localhost:49573/assets/js/scripts.js:9
.success@http://localhost:49573/:462
x.Callbacks/c@http://localhost:49573/assets/js/jquery-1.10.2.min.js:4
x.Callbacks/p.fireWith@http://localhost:49573/assets/js/jquery-1.10.2.min.js:4
k@http://localhost:49573/assets/js/jquery-1.10.2.min.js:6
.send/r@http://localhost:49573/assets/js/jquery-1.10.2.min.js:6

This format provides the calling function, URL, and successive calling functions.

For modern browsers, a more straightforward method is available:

console.trace(); // (MDN Reference)

This function captures a stack trace and displays it in the console.

An alternative option was proposed in the original thread:

function stacktrace() { 
  function st2(f) {
    return !f ? [] : 
        st2(f.caller).concat([f.toString().split('(')[0].substring(9)   '('   f.arguments.join(',')   ')']);
  }
  return st2(arguments.callee.caller);
}

This function recursively traverses the call stack and constructs a stack trace string.

By implementing these methods, developers can effectively obtain stack traces for custom JavaScript exceptions, enabling more robust error handling and debugging.