A JavaScript utility that can be used to determine what function and file your function was called from

getFnCaller.js

/**
 * A JavaScript utility that can be used to determine what function
 * and file your function was called from. Useful for debugging
 * large/complex codebases.
 *
 * @returns {{
 *   fnName: string | void;
 *   filePath: string;
 *   lineNumber: number;
 *   columnNumber: number;
 * } | null}
 */
export function getFnCaller() {
  const error = new Error();
  if (!error.stack) return null;

  // index 0 is the error name
  // index 1 is this fn's stack line
  // index 2 is the fn that called this fn
  // index 3, finally, is the one that called this fn's caller
  const callerLine = error.stack.split('\n')[3];
  if (!callerLine) return null;

  const nodeCwd =
    typeof process != 'undefined' && typeof process?.cwd === 'function'
      ? process.cwd() + '/'
      : '';
  const trimmedCallerLine = callerLine.split('at ')[1].replace(nodeCwd, '');
  const [, fnName, filePath, lineNumber, columnNumber] =
    trimmedCallerLine.match(/^(?:async )?(?:(.+) \()?(?:[^:]+:\/\/)?([^:]+):(\d+):(\d+)\)?$/) || [];

  if (filePath && lineNumber && columnNumber) {
    return {
      fnName,
      filePath,
      lineNumber: parseInt(lineNumber),
      columnNumber: parseInt(columnNumber),
    };
  }

  return null;
}