a function that dispatches to other functions based on signature

Dispatcher.js

function Dispatcher() {
  var signatures = [], functions = [];

  function fn() {

    var
      args = arguments,
      argNo,
      arity = args.length,

      sigs = signatures[ arity ],
      sigNo = sigs ? sigs.length : 0,

      match = fn.noMatch;
    
    eachSig: while ( sigNo-- ) {
      argNo = arity;
      
      while ( argNo-- )
        if ( sigs[ sigNo ][ argNo ]( args[ argNo ] ) !== true )
          continue eachSig;
      
      match = functions[ arity ][ sigNo ];
      break;
    }
    
    return match.apply( this, args );
  };

  fn.add = function( args, target ) {
    var arity = args.length;
    
    if ( !signatures[ arity ] ) {
      signatures[ arity ] = [];
      functions[ arity ] = [];
    }

    signatures[ arity ].push( args );  
    functions[ arity ].push( target );
    
    return fn;
  };
  
  fn.noMatch = function() { throw "Argument signature not supported." };
  
  return fn;
}