JavaScript 中的不完全函数

function array(a,n){
                return Array.prototype.slice.call(a,n || 0);
            }
            //the arguments to this function are passed on the left
            function particalLeft(f){
                var args = arguments;
                return function(){
                    var a = array(args,1);
                    a = a.concat(array(arguments));
                    return f.apply(this,a);
                }
            }
            //the arguments to this function are passed on the right
            function particalRight(f){
                var args = arguments;
                return function(){
                    var a = array(arguments);
                    a = a.concat(array(args, 1));
                    return f.apply(this, a);
                }
            }
            //The arguments to this function serve as a templete, Undefined values in the argument list are filled in with values from the inner set
            function partical(f){
                var args = arguments;
                return function(){
                    var a = array(arguments);
                    var length = a.length;
                    var j = 0;
                    for(var i = 0; i< length; i++){
                        if(a[i] === undefined){
                            a[i] = arguments[j++];
                        }
                    }
                    a = a.concat(array(arguments,j));
                    return f.apply(this,a);
                }
            }
            function f(x,y,z){
                return x*(y-z);
            }
            var result1 = particalLeft(f,2,3)(4);
            var result2 = particalRight(f,2)(3,4);
            var result3 = partical(f,undefined)(2,3,4);
            console.log(result1);
            console.log(result2);
            console.log(result3);