prepare_stack_trace.js

'use strict';

const debug = require('internal/util/debuglog').debuglog('source_map');
const { findSourceMap } = require('internal/source_map/source_map_cache');
const { overrideStackTrace } = require('internal/errors');

// Create a prettified stacktrace, inserting context from source maps
// if possible.
const ErrorToString = Error.prototype.toString; // Capture original toString.
const prepareStackTrace = (globalThis, error, trace) => {
  // API for node internals to override error stack formatting
  // without interfering with userland code.
  // TODO(bcoe): add support for source-maps to repl.
  if (overrideStackTrace.has(error)) {
    const f = overrideStackTrace.get(error);
    overrideStackTrace.delete(error);
    return f(error, trace);
  }

  const decoratedTrace = decorateCallSites(error, trace);

  // `globalThis` is the global that contains the constructor which
  // created `error`.
  if (typeof globalThis.Error.prepareStackTrace === 'function') {
    return globalThis.Error.prepareStackTrace(error, decoratedTrace);
  }

  const errorString = ErrorToString.call(error);

  if (decoratedTrace.length === 0) {
    return errorString;
  }
  const preparedTrace = decoratedTrace.map((t, i) => {
    let str = i !== 0 ? '\n    at ' : '';
    str = `${str}${t}`;
    if (t.getOriginalLineNumber) {
      str += `\n        -> ${
        t.getOriginalFileName()
      }:${
        t.getOriginalLineNumber()
      }:${t.getOriginalColumnNumber()}`;
    }
    return str;
  });
  return `${errorString}\n    at ${preparedTrace.join('')}`;
};

function decorateCallSites(error, trace) {
  const { SourceMap } = require('internal/source_map/source_map');
  return trace.map((t) => {
    try {
      const sourceMap = findSourceMap(t.getFileName(), error);
      if (sourceMap && sourceMap.data) {
        const sm = new SourceMap(sourceMap.data);
        // Source Map V3 lines/columns use zero-based offsets whereas, in
        // stack traces, they start at 1/1.
        const [, , url, line, col] =
                   sm.findEntry(t.getLineNumber() - 1, t.getColumnNumber() - 1);
        if (url && line !== undefined && col !== undefined) {
          return decorateCallSite(t, url.replace('file://', ''), line + 1,
                                  col + 1);
        }
      }
    } catch (err) {
      debug(err.stack);
    }
    return decorateCallSite(t, t.getFileName(), t.getLineNumber(),
                            t.getColumnNumber());
  });
}

function decorateCallSite(callSite, fileName, lineNumber, columnNumber) {
  callSite.getOriginalFileName = () => {
    return fileName;
  };
  callSite.getOriginalLineNumber = () => {
    return lineNumber;
  };
  callSite.getOriginalColumnNumber = () => {
    return columnNumber;
  };
  return callSite;
}

module.exports = {
  prepareStackTrace,
};