Benchmark

bench.js

function bench(stack, numRuns) {

  var results = {};

  var i, j, fn, timestamp;
  for (i = 0; i < stack.length; ++i) {
    results[stack[i].name] = {
      sum: 0,
      mean: 0
    };
    fn = stack[i];
    for (j = 0; j < numRuns; ++j) {
      timestamp = process.hrtime();
      fn();
      timestamp = process.hrtime(timestamp);
      // results[stack[i].name].sum += timestamp[0] + timestamp[1] / 1e9;
      results[fn.name].sum += timestamp[1];
    }
    results[fn.name].mean = results[fn.name].sum / numRuns;
  }
  return results;
}

var count = 1000;
var stack = [
  function test_empty_ref_1() {},
  function test_normalForLoop() {
    var length = count;
    for (var i = 0; i < length; ++i) {}
  },
  function test_predefineForLoop() {
    var i, length = count;
    for (i = 0; i < length; ++i) {}
  },
  function test_whileLoop() {
    var i, length = count;
    while (++i < length) {}
  },
  function test_doWhileLoop() {
    var i, length = count;
    do {} while (++i < length);
  },
  function test_concat() {
    var x = '1' + '2' + '3' + '4' + '5' + '6' + '7' + '8' + '9' + '0';
  },
  function test_join() {
    var x = [];
    x.push('1', '2', '3', '4', '5', '6', '7', '8', '9', '0');
    x = x.join('');
  },
  function test_parseInt() {
    var x = '1234';
    x = parseInt(x, 10);
  },
  function test_castInt() {
    var x = '1234';
    x = +x;
  },
  function test_empty_ref_2() {}
];

var i, results = bench(stack, 1e6);
for (i = 0; i < stack.length; ++i) {
  console.log(stack[i].name);
  console.log('                   mean: %s', results[stack[i].name].mean);
}

results.markdown

test_empty_ref_1
                   mean: 681.747666
test_normalForLoop
                   mean: 2859.219527
test_predefineForLoop
                   mean: 2839.495833
test_whileLoop
                   mean: 683.830738
test_doWhileLoop
                   mean: 668.78133
test_concat
                   mean: 949.704838
test_join
                   mean: 1066.524476
test_parseInt
                   mean: 690.45971
test_castInt
                   mean: 765.852366
test_empty_ref_2
                   mean: 653.450886