a example about closure

closure

function decorate(fn, decorator) {
  return function() {
        var args = Array.prototype.slice.apply(arguments);
        args.unshift(fn);
		return decorator.apply(null, args);
	}
}
	
function total(x, y) {
    return x + y;
}

function ph(fn, x, y) {
    var n = fn.call(null, x, y);
    return n * n;
}

var pp = decorate(total,ph);

console.log( total(3, 5) ); //8
console.log( pp(3, 5) ); //64