a javascript puzzle , and try to work out the alert result

puzzle.js

  	var output1 = new Array;
		var output2, output3;
	 	var pushArr = function (c) {
	 		if (!c) {
	 			c = 0;
	 		}
	 		output1.push(c);
	 	};
	 	var a = 1;
	 	pushArr(a);
	 	var d = (function (a) {
		 	pushArr(a);
		 	var a = 2;
		 	pushArr(a);
		 	var b = function () {
		 		pushArr(a);
		 		var a = 3;
 			 	pushArr(a);
		 		return function (a) {
		 			pushArr(a);
		 			var a = 4;
		 			pushArr(a);
		 		}
		 	}
		 	pushArr(a);
		 	a = b()(a);
		 	pushArr(a);
		 	return function () {
		 		pushArr(a);
		 		a = 5;
		 		pushArr(a);
		 		return a;
		 	};
	 	})(a);
	 	pushArr(a);
	 	a = d();
	 	pushArr(a);
	 	output2 = output1.slice(0);
	 	output3 = output1;
	 	output3.sort(function (a, b) {
	 		return a - b;
	 	});
	 	var al = function () {
	 		alert(output1.slice(a).concat(output2, output3.slice(0-a)).join(""));
	 	}