join v concat

joinvconcat.js

(function() {
  var start = Date.now();
  var i = 1000000;
  while (i--) {
    var str = '';
    str += 'a';
    str += 'a';
    str += 'a';
    str += 'a';
    str += 'a';
    str += 'a';
    str += 'a';
    //str += 'a';
    //str += 'a';
    //str += 'a';
  }
  console.log('CONCAT:', Date.now() - start);
})();

(function() {
  var start = Date.now();
  var i = 1000000;
  while (i--) {
    var str = [];
    str.push('a');
    str.push('a');
    str.push('a');
    str.push('a');
    str.push('a');
    str.push('a');
    str.push('a');
    //str.push('a');
    //str.push('a');
    //str.push('a');
    str.join('');
  }
  console.log('JOIN:', Date.now() - start);
})();

(function() {
  var start = Date.now();
  var i = 1000000;
  while (i--) {
    [
      'a',
      'a',
      'a',
      'a',
      'a',
      'a',
      'a'
    ].join('');
  }
  console.log('JOIN LITERAL:', Date.now() - start);
})();