parseStackTrace() — react Function Reference

Source Code

packages/react-server/src/ReactFlightStackConfigV8.js lines 174–253

export function parseStackTrace(
  error: Error,
  skipFrames: number,
): ReactStackTrace {
  // We can only get structured data out of error objects once. So we cache the information
  // so we can get it again each time. It also helps performance when the same error is
  // referenced more than once.
  const existing = stackTraceCache.get(error);
  if (existing !== undefined) {
    return existing;
  }
  // We override Error.prepareStackTrace with our own version that collects
  // the structured data. We need more information than the raw stack gives us
  // and we need to ensure that we don't get the source mapped version.
  collectedStackTrace = null;
  framesToSkip = skipFrames;
  const previousPrepare = Error.prepareStackTrace;
  Error.prepareStackTrace = collectStackTrace;
  let stack;
  try {
    // eslint-disable-next-line react-internal/safe-string-coercion
    stack = String(error.stack);
  } finally {
    Error.prepareStackTrace = previousPrepare;
  }

  if (collectedStackTrace !== null) {
    const result = collectedStackTrace;
    collectedStackTrace = null;
    stackTraceCache.set(error, result);
    return result;
  }

  // If the stack has already been read, or this is not actually a V8 compatible
  // engine then we might not get a normalized stack and it might still have been
  // source mapped. Regardless we try our best to parse it. This works best if the
  // environment just uses default V8 formatting and no source mapping.

  if (stack.startsWith('Error: react-stack-top-frame\n')) {
    // V8's default formatting prefixes with the error message which we
    // don't want/need.
    stack = stack.slice(29);
  }
  let idx = stack.indexOf('react_stack_bottom_frame');
  if (idx !== -1) {
    idx = stack.lastIndexOf('\n', idx);
  }
  if (idx !== -1) {
    // Cut off everything after the bottom frame since it'll be internals.
    stack = stack.slice(0, idx);
  }
  const frames = stack.split('\n');
  const parsedFrames: ReactStackTrace = [];
  // We skip top frames here since they may or may not be parseable but we
  // want to skip the same number of frames regardless. I.e. we can't do it
  // in the caller.
  for (let i = skipFrames; i < frames.length; i++) {
    const parsed = frameRegExp.exec(frames[i]);
    if (!parsed) {
      continue;
    }
    let name = parsed[1] || '';
    let isAsync = parsed[8] === 'async ';
    if (name === '<anonymous>') {
      name = '';
    } else if (name.startsWith('async ')) {
      name = name.slice(5);
      isAsync = true;
    }
    let filename = parsed[2] || parsed[5] || '';
    if (filename === '<anonymous>') {
      filename = '';
    }
    const line = +(parsed[3] || parsed[6]);
    const col = +(parsed[4] || parsed[7]);
    parsedFrames.push([name, filename, line, col, 0, 0, isAsync]);
  }
  stackTraceCache.set(error, parsedFrames);
  return parsedFrames;
}