popomore/replace-vs-split-join.js

## replace-vs-split-join.js
var bench = require('bench');
var compare = {};
var data = {};

// 先安装 bench
// 10^5 基本小于 1 ms，所以对比 10^5 到 10^6 之间的数
for (var i = 1; i <= 10; i++) {
  var count = 100000 * i;
  (function(count) {
    var content = createContent(count);
    compare['replace1 ' + count] = replace1.bind(null, content);
    compare['replace2 ' + count] = replace2.bind(null, content);
  })(count);
}

exports.compare = compare;
exports.done = done;

function replace1(content) {
  var name = 'replace1 ' + content.length;
  var begin = new Date().getTime();
  content.replace(/<\/(head|body)>/g, function(all, match) {
    return match === 'head' ? 'h' : 'b' + all;
  });
  var time = new Date().getTime() - begin;
  save(name, time);
  console.log(name + ' ' + time);
}

function replace2(content) {
  var name = 'replace2 ' + content.length;
  var begin = new Date().getTime();
  content.split('</head>').join('h</head>').split('</body>').join('b</body>');
  var time = new Date().getTime() - begin;
  save(name, time);
  console.log(name + ' ' + time);
}

function createContent(count) {
  var head = '', body = '';
  while (count > 0) {
    head += 'h';
    body += 'b';
    count--;
  }
  return '<html><head>' + head + '</head><body>' + body + '</body></html>';
}

function save (name, time) {
  if (!data[name]) data[name] = {value: 0, count: 0};
  data[name].value += time;
  data[name].count++;
}

function done(d) {
  bench.show(d);
  console.log('');
  console.log('');
  Object.keys(data)
    .sort(function(a, b) {
      var a1 = a.split(' ');
      var b1 = b.split(' ');
      if (a1[0] !== b1[0]) {
        return a1[0] > b1[0] ? 1 : -1;
      }
      return Number(a1[1]) - Number(b1[1]);
    })
    .forEach(function(key) {
      var o = data[key];
      console.log(key + ' ' + (o.value / o.count));
    });
}

bench.runMain();