mapError

The mapError() function extracts information from an Error object as a human-readable array of strings. This includes the error name, message, and a call stack.

If --enable-stack-traces is specified during the build, the call stack will be mapped using source maps.

If --enable-stack-traces is specified and --exclude-sources is not specified during the build, then this will also include a code dump of neighboring lines of user code.

Syntax

mapError(error)

Parameters

• error _: Error _ or string
  • The error to retrieve information about. If a string is provided, then it is first converted to an Error.

Return value

Returns an array of strings.

Examples

In this example, build the application using the --enable-stack-traces flag.

addEventListener('fetch', e => e.respondWith(handler(e)));
async function handler(event) {
  try {
    throw new TypeError('foo');
  } catch (err) {
    console.error(mapError(err));
  }
  return new Response('ok');
}

The following is output to the error log.

TypeError: foo
  at handler (src/index.ts:4:11)
      1 | addEventListener('fetch', e => e.respondWith(handler(e)));
      2 | async function handler(event) {
      3 |   try {
>     4 |     throw new TypeError('foo');
                    ^
      5 |   } catch (err) {
      6 |     console.error(mapError(err));
      7 |   }
  at src/index.ts:1:45