JS數組排序的問題

var arr1 = new Array([1,2000,5,40,3]);
		var arr2 = new Array([1],[2000],[5],[40],[3]);
		var arr3 = new Array([1],[2],[5],[4],[3]);
		var arr4 = [1,2000,5,40,3];

		document.write(arr1.length+"<br/>");
		arr1.sort();
		document.write(arr1+"<br/>");

		document.write(arr2.length+"<br/>");
		arr2.sort();
		document.write(arr2+"<br/>");

		document.write(arr3.length+"<br/>");
		arr3.sort();
		document.write(arr3+"<br/>");

		document.write(arr4.length+"<br/>");
		arr4.sort(compareASC);
		document.write(arr4+"<br/>");

		function compareASC(a, b){
			return a - b;
		}

結果：

1

1,2000,5,40,3

5

1,2000,3,40,5

5

1,2,3,4,5

5
1,3,5,40,2000