↑
Main Page

The reverse() method

if (iNum1 < iNum2) {

return –1;

} else if (iNum1 > iNum2) {

return 1;

} else {

return 0;

}

If you apply this comparison function to the earlier example, the correct result is returned:

var arr = [3, 32, 2, 5]

arr.sort(compareIntegers);

alert(arr.toString()); //outputs “2,3,5,32”

This example now outputs the numbers in correct order (2, 3, 5, 32).

The reverse() method

You were introduced to the

reverse()

method, which simply reverses the order of the items in an

array, in Chapter 3, “Object Basics.” In this chapter, you learn that the

reverse()

method is an essential

part of sorting.

So, if you use a comparison function that sorts in ascending order, you can easily change the sort to

descending order by using the

reverse()

method after the

sort()

method:

var arr = [3, 32, 2, 5]

arr.sort(compareIntegers);

alert(arr.toString()); //outputs “2,3,5,32”

arr.reverse();

alert(arr.toString()); //outputs “32,5,3,2”

Of course, this is an extra step added to the sorting process, and there is certainly nothing wrong with

creating two comparison functions whenever sorting is necessary. Just keep in mind that whenever an

array is already sorted in one direction, it is much faster to use

reverse()

to sort it in the opposite

direction than it is to call

sort()

once again.

Sorting a One-Column Table

Now you begin the task at hand, sorting a table. The simplest case is to sort a table with just one column

and, therefore, just one data type. The best way to set up a table for sorting is to create a

ele-

ment for the table header rows and a

element for the rows that contain data:

<thead>

<tr>

</tr>

</thead>

369

Sorting Tables

15_579088 ch12.qxd 3/28/05 11:40 AM Page 369