caller.js

module.exports = function () {
    // see https://code.google.com/p/v8/wiki/JavaScriptStackTraceApi
    var origPrepareStackTrace = Error.prepareStackTrace;
    Error.prepareStackTrace = function (_, stack) { return stack; };
    var stack = (new Error()).stack;
    Error.prepareStackTrace = origPrepareStackTrace;
    return stack[2].getFileName();
};