/**
 * Copyright (c) 2017-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @flow
 * @format
 */

/* global performance */

/**
 * Polyfill for performance.now that works both on Atom (chrome) and node.
 * It returns a monotonically increasing timer in milliseconds.
 *
 * Usage:
 *   const now = performanceNow();
 *   // ... code you want to benchmark ...
 *   const timeItTookInMilliseconds = performanceNow() - now;
 */

export default (typeof performance !== 'undefined'
  ? (): number => performance.now()
  : (): number => {
      const [seconds, nanoseconds] = process.hrtime();
      return seconds * 1000 + nanoseconds / 1000000;
    });