gistfile1.js

var data = [];

describe('fast array', function(){
  it('setup', function() {
    var max = 9 * (1000 * 1000);
    while(data.length < max) {
      if(data.length === max / 2) data.push(['random', 'random value']);
      else data.push(['key', 'value']);
    }
    
    data.where = function (fn) {
      var res = [];
      for(var i = 0; i < this.length; i++) {
        var t = this[i];
        if(fn(t[0], t[1])) res.push(t);
      }
    };
    
    // build fast array
    var stack = {};
    var pointer = 0;
    
    for(var i = 0; i < data.length; i++) {
      stack[pointer++] = data[i][0];
      stack[pointer++] = data[i][1];
    }
    
    data.where2 = function (fn) {
      var res = [];
      var max = pointer;
      var i = 0;
      while(true) {
        var key = stack[i++];
        var value = stack[i++];
        if(key === 'random') {
          res.push([key, value]);
          break;
        }
      }
      
    };
  })
  
  it('inline array', function() {
    var res = data.where2(function (k, v) {
      return k === 'random';
    });
  })
  
  
  it('regular array', function() {
    var res = data.where(function (k, v) {
      return k === 'random';
    });
  })
})