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Sorting Tables

In most applications, sorting lists and tables is a normal procedure that you might use on a daily

basis. When you checking your e-mail, you probably have the table set up to sort by descending

order on the date column, placing the most recent e-mails at the top. It was only a matter of time

before this paradigm made its way onto the Web.

Traditionally, sorting on the Web involves a round-trip to the server with the request indicating

which column should be sorted and in what direction. However, JavaScript enables you to create

the same functionality on the client. Using JavaScript, it’s possible to use sortable tables and also

eliminate the need for costly server-side processing.

The Starting Point — Arrays

Back in Chapter 3, “Object Basics,” you were introduced to the

Array

object and its

sort()

method.

You may remember that the

sort()

method sorts in ascending order by the ASCII character code of

each item, meaning that numbers are also sorted by their string equivalents:

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

arr.sort();

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

The previous example displays

“2,3,32,5”

when the array is output. Luckily, JavaScript doesn’t

leave you stranded. The

sort()

method can also be given a single argument: a comparison func-

tion to tell the sorting algorithm when one value is greater than, less than, or equal to another value.

comparison function

is a function with a specific algorithm. It’s helpful to take a look at a basic

comparison function before continuing with the explanation:

function comparison_function(value1, value2) {

if (value1 < value 2) {

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