Javascript exception tracebacks

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Working with browser Javascript on mobile devices, I found myself needing to report exceptions back to a server. (It’s hard to see the browser console log on a mobile device without connecting it to a desktop machine).

Here’s what I did to make a suitable object that can be serialized.

 function formatException(exception, callback) {
    const error = {}
    if (exception && 
        exception.constructor &&
        exception.constructor.name)
                   error.type = exception.constructor.name
    error.code = exception.code
    error.name = exception.name
    error.message = exception.message
    if (exception.label) error.label = exception.label
    error.stack = []
    StackTrace.fromError(new Error(exception))
      .then(stackframes => {
        stackframes.map(function (frame, depth) {
          if (depth !== 0)
            error.stack.push(frame.toString())
        })
        postObject({type: 'error', error})
      })
      .catch(er => console.error('stack?', exception, er))
  }

...
catch (exception) {
    formatException(exeception, console.log)
}

To use this you’ll need stacktrace.js loaded in your web page.

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