两层继承

class_2.js

'use strict';

const Benchmark = require('benchmark');
const benchmarks = require('beautify-benchmark');
const suite = new Benchmark.Suite();

const util = require('util');
const assert = require('assert');

class A {
  calculate() {
    return 1000000 * 1000000;
  }
}

class B extends A {}

class C extends B {}

// add tests
suite
  .add('class A', function() {
    const a = new A();
    a.calculate();
  })
  .add('class B', function() {
    const b = new B();
    b.calculate();
  })
  .add('class C', function() {
    const c = new C();
    c.calculate();
  })
  .on('cycle', function(event) {
    benchmarks.add(event.target);
  })
  .on('start', function() {
    console.log('\n  node version: %s, date: %s\n  Starting...', process.version, Date());
  })
  .on('complete', function done() {
    benchmarks.log();
  })
  .run({ async: false });

// node version: v8.9.4, date: Thu Jan 25 2018 19:41:40 GMT+0800 (CST)
// Starting...
// 3 tests completed.

// class A x 151,005,771 ops/sec ±1.33% (82 runs sampled)
// class B x  31,828,118 ops/sec ±1.31% (82 runs sampled)
// class C x  29,303,519 ops/sec ±2.23% (79 runs sampled)