Function bind.js

Function bind.js

/*
  uses compilation to optimize `Function#bind`, but not real `bind` which in fact - `carry`
  inlines consts.
*/

var defaultThis = (function(){ return this })();

this._fastBind = (function()
{
  var _quoteString = function(s)
  {
    return s.replace(
      /\n|\r|\\|\"/g, function(c)
      {
        switch(c)
        {
          case '\n': return '\\n';
          case '\r': return '\\r';
          case '\\': return '\\\\';
          case '\"': return '\\\"';
        }
      }
    );
  };
  
  return function(_fn, that, args)
  {
    var _ret;
    
    if(args == null)
    {
      _ret = (that === defaultThis) 
        ? function(){ return (arguments.length > 0) ? _fn.apply(this, arguments) : _fn.call(this) }
        : function(){ return (arguments.length > 0) ? _fn.apply(that, arguments) : _fn.call(that) }
      ;  
    }
    else
    {
      var argsStr = '_fn,', callStr = '', nonConstArgs = [_fn], j = 1;
      
      if(that !== defaultThis)
      {  
        callStr = '.call(that,';
        argsStr += 'that,';
        nonConstArgs[j++] = that;
      }
      else  
      {
        callStr = '(';
      }
      
      var i = -1; while(++i < args.length)
      {
        var a = args[i];
        
        if(a === null)
        {  
          callStr += 'null,';
        }
        else
        {
          switch(typeof(a))
          {
            case 'string': 
              callStr += '"' + _quoteString(a) + '",';
              break;
            case 'number': 
            case 'boolean':
            case 'undefined':
              callStr += '' + a + ',';
              break;
            default:
              callStr += 'a' + i + ',';
              nonConstArgs[j++] = a[i];
              argsStr += 'a' + i + ','
          }
        }  
      }
      
      callStr = callStr.slice(0, -1);
      argsStr = argsStr.slice(0, -1);
      
      _ret = Function(argsStr, 'return function(){ return _fn' + callStr + ') }').apply(null, nonConstArgs);
    }
    
    _ret.prototype = _fn.prototype;
    
    return _ret;
  };
})();  

this._basicBind = function(_fn, that, args)
{
  var _ret;
  
  if(that !== defaultThis)
  {
    _ret = (args != null) 
      ? function(){ return _fn.apply(that, args); }
      : function(){ return (arguments.length > 0) ? _fn.apply(that, arguments) : _fn.call(that); }
    ;
  }
  else
  {
    _ret = (args != null) 
      ? function(){ return _fn.apply(this, args); }
      : function(){ return (arguments.length > 0) ? _fn.apply(this, arguments) : _fn.call(this); }
    ;
  }

  _ret.prototype = _fn.prototype;
  
  return _ret;
};

var _fn = function(a, b, c)
{
  return a + b + c;
};

var args = [1, '', {}, null, function(){}];

_speedTest({
  'native bind': Function.prototype.bind && function(n)
  {
    var _fnB = _fn.bind.apply(_fn, [window].concat(args)), a;
    while(n--)
      a += _fnB();
      
  },
  '_basicBind': function(n)
  {
    var _fnB = _basicBind(_fn, window, args), a;
    while(n--)
      a += _fnB();
      
  },
  '_fastBind': function(n)
  {
    var _fnB = _fastBind(_fn, window, args), a;
    while(n--)
      a += _fnB();
      
  }
}, 100000);

/*
  chrome11 1000000
    _basicBind: 3397 ms
    _fastBind: 1095 ms
    native bind: 5991 ms
  ie8 60000
    _basicBind: 721 ms
    _fastBind: 581 ms
    native bind: skipped
  opera 10.62 400000
    _basicBind: 1329 ms
    _fastBind: 527 ms
    native bind: skipped  
  ff3.6 100000
    _basicBind: 927 ms
    _fastBind: 384 ms
    native bind: skipped
  ff4 800000
    _basicBind: 893 ms
    _fastBind: 922 ms
    native bind: 2617 ms
  safari5 500000
    _basicBind: 1588 ms
    _fastBind: 887 ms
    native bind: skipped    
    
*/