Caching Fibonacci (JavaScript)

fib.js

var fib = (function() {
  var fibArr = [];

  var calcFib = function( n ) {
    return ( n <= 1 ? 1 : (fib( n - 1 ) + fib( n - 2 )));
  };

  return function( n ) {
  	if( !fibArr[ n ] ) {
  	  fibArr[ n ] = calcFib( n );
  	}
  	
  	return fibArr[ n ];
  };
})();