如果我需要在大型数据集中按字符串键随机查找，我试图了解是使用JS Object还是Map(

我写了一个简单的基准测试http://jsperf.com/javascript-objects-vs-map-performance结果表明，在Chrome（V8）中，对象的性能比地图高出约2倍。然而，我检查了其他浏览器，结果却相反。为什么它们在不同的浏览器/引擎中如此不同？

我还在Node中写了一个类似的测试。JS和我看不到类似的结果(测试用例6花费的时间比测试用例4多得多):

var now = require("performance-now");

var mapKeyValue = new Map();
var mapStringKeyValue = new Map();
var objectKeyValue = {};
var n = 10000;
var testSamples = 100;

var firstRow = 0;
var firstRowString = firstRow + "";

var middleRow = Math.floor(n / 2);
var middleRowString = middleRow + "";

var lastRow = n - 1;
var lastRowString = lastRow + "";

var nonExist = n * 2;
var nonExistString = nonExist + "";

function makeid() {
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  for (var i = 0; i < 20; i++)
    text += possible.charAt(Math.floor(Math.random() * possible.length));

  return text;
}

for (var i = 0; i < n; i++) {
  var value = makeid();
  mapKeyValue.set(i, value);
  mapStringKeyValue.set(i + "", value);
  objectKeyValue[i + ""] = value;
}

var t0, t1;

var averages = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];

for (var j = 0; j < testSamples; j++) {
  var k = 0;
  t0 = now();
  mapKeyValue.get(firstRow);
  t1 = now();
  averages[k++] += (t1 - t0);

  t0 = now();
  mapStringKeyValue.get(firstRowString);
  t1 = now();
  averages[k++] += (t1 - t0);

  t0 = now();
  objectKeyValue[firstRowString];
  t1 = now();
  averages[k++] += (t1 - t0);


  t0 = now();
  mapKeyValue.get(middleRow);
  t1 = now();
  averages[k++] += (t1 - t0);

  t0 = now();
  mapStringKeyValue.get(middleRowString);
  t1 = now();
  averages[k++] += (t1 - t0);

  t0 = now();
  objectKeyValue[middleRowString];
  t1 = now();
  averages[k++] += (t1 - t0);


  t0 = now();
  mapKeyValue.get(lastRow);
  t1 = now();
  averages[k++] += (t1 - t0);


  t0 = now();
  mapStringKeyValue.get(lastRowString);
  t1 = now();
  averages[k++] += (t1 - t0);

  t0 = now();
  objectKeyValue[lastRowString];
  t1 = now();
  averages[k++] += (t1 - t0);


  t0 = now();
  mapKeyValue.get(nonExist);
  t1 = now();
  averages[k++] += (t1 - t0);

  t0 = now();
  mapStringKeyValue.get(nonExistString);
  t1 = now();
  averages[k++] += (t1 - t0);

  t0 = now();
  objectKeyValue[nonExistString];
  t1 = now();
  averages[k++] += (t1 - t0);
}

console.log("Test samples number " + testSamples);

for (var i = 0; i < averages.length; i++) {
  averages[i] /= testSamples;
  console.log("Test case " + (i + 1) + " took in average " + (averages[i] * 1000000) + " ns");
}

Test samples number 100
Test case 1 took in average 2050.269999999692 ns
Test case 2 took in average 751.2899999997202 ns
Test case 3 took in average 567.3000000004081 ns
Test case 4 took in average 727.2699999999688 ns
Test case 5 took in average 4760.029999999489 ns
Test case 6 took in average 1939.3400000004135 ns
Test case 7 took in average 673.549999999885 ns
Test case 8 took in average 689.3600000002564 ns
Test case 9 took in average 541.3700000001143 ns
Test case 10 took in average 1146.0599999999843 ns
Test case 11 took in average 3096.7699999998285 ns
Test case 12 took in average 644.7400000000058 ns

如果您对如何改进基准并使其更准确有任何想法，请告诉我。谢谢。