Parse V8 Stack Traces Into Frames

export interface StackFrame {
  readonly functionName: string | null;
  readonly file: string | null;
  readonly line: number | null;
  readonly column: number | null;
  readonly native: boolean;
  readonly async: boolean;
}

export function parseStackTrace(stack: string): StackFrame[] {
  if (typeof stack !== "string") throw new TypeError("stack must be a string");
  const frames: StackFrame[] = [];
  for (const rawLine of stack.split("\n")) {
    const line = rawLine.trim();
    if (!line.startsWith("at ")) continue;
    const frame = parseFrame(line.slice(3));
    if (frame !== null) frames.push(frame);
  }
  return frames;
}

function parseFrame(value: string): StackFrame | null {
  if (value === "native") {
    return { functionName: null, file: null, line: null, column: null, native: true, async: false };
  }
  let text = value;
  let isAsync = false;
  if (text.startsWith("async ")) {
    isAsync = true;
    text = text.slice(6);
  }
  const locationMatch = /^(.*?) \((.+):(\d+):(\d+)\)$/.exec(text);
  if (locationMatch !== null) {
    return {
      functionName: normalizeName(locationMatch[1] ?? ""),
      file: locationMatch[2] ?? null,
      line: Number(locationMatch[3]),
      column: Number(locationMatch[4]),
      native: false,
      async: isAsync,
    };
  }
  const bareMatch = /^(.+):(\d+):(\d+)$/.exec(text);
  if (bareMatch !== null) {
    return {
      functionName: null,
      file: bareMatch[1] ?? null,
      line: Number(bareMatch[2]),
      column: Number(bareMatch[3]),
      native: false,
      async: isAsync,
    };
  }
  return {
    functionName: normalizeName(text),
    file: null,
    line: null,
    column: null,
    native: false,
    async: isAsync,
  };
}

function normalizeName(value: string): string | null {
  const name = value.trim();
  if (name === "" || name === "eval") return null;
  return name;
}

const stack = [
  "Error: boom",
  "    at fetchUser (/app/src/users.js:42:13)",
  "    at async loadProfile (/app/src/profile.js:8:20)",
  "    at /app/src/index.js:3:1",
  "    at native",
].join("\n");
console.log(parseStackTrace(stack));
console.log(parseStackTrace("Error: empty"));