Logging module, file, and line number of caller

gistfile1.js

var util = require('util');

const STACK_FRAME_RE = new RegExp(/at ((\S+)\s)?\(?([^:]+):(\d+):(\d+)/);
const THIS_FILE = __filename.split('/')[__filename.split('/').length - 1];

var Logger = module.exports = function Logger() {
  // I like pie
};

Logger.prototype = {
  /**
   * Return the function name, module, line, and column of the code
   * that called into this logger.
   */
  _getCaller: function() {
    var err = new Error();
    Error.captureStackTrace(err);

    // Throw away the first line of the trace
    var frames = err.stack.split('\n').slice(1);

    // Find the first line in the stack that doesn't name this module.
    var callerInfo = null;
    for (var i = 0; i < frames.length; i++) {
      if (frames[i].indexOf(THIS_FILE) === -1) {
        callerInfo = STACK_FRAME_RE.exec(frames[i]);
        break;
      }
    }

    if (callerInfo) {
      return {
        function: callerInfo[2] || null,
        module: callerInfo[3] || null,
        line: callerInfo[4] || null,
        column: callerInfo[5] || null
      };
    }
    return null;
  },

  /**
   * for example ...
   */
  emit: function(message) {
    var caller = this._getCaller();
    console.log(util.format("%s %s, line %d: %s",
                            caller.module, caller.function, caller.line, message));
  },
};