Show HN: Fast.js – faster reimplementations of native JavaScript functions(github.com)

  exports.forEach = function fastForEach (subject, fn, thisContext) {
    var length = subject.length,
        i;
    for (i = 0; i < length; i++) {
      fn.call(thisContext, subject[i], i, subject);
    }
  };

    // new benchmark in bench/for-each.js    

    exports['explicit iteration'] = function() {
        acc = 0;
        for (var j=0; j<input.length; ++j) {
            acc += input[j];
        }
    }

  Native .forEach() vs fast.forEach() vs explicit iteration
    ✓  Array::forEach() x 2,101,860 ops/sec ±1.50% (79 runs sampled)
    ✓  fast.forEach() x 5,433,935 ops/sec ±1.12% (90 runs sampled)
    ✓  explicit iteration x 28,714,606 ops/sec ±1.44% (87 runs sampled)

    Winner is: explicit iteration (1266.15% faster)

    blah | 0; // fast!
    Math.floor(blah); // slow(er)! (except on FF nightly)

  exports.map = function fastMap (subject, fn, thisContext) {
    var i = subject.length,
        result = new Array(i);
    if (thisContext) {
      while (i--) {
        result[i] = fn.call(thisContext, subject[i], i, subject);
      }
    } else {
      while (i--) {
        result[i] = fn(subject[i], i, subject);
      }
    }
    return result;
  };