JavaScript Examples Bible - UserWorks Technologies

The Array Object
(Chapter 37)
Whenever you are faced with having to manage any
kind of list or series of related data chunks, the first
technique to turn to is stuffing those chunks into an array.
Once the data is inside an array, your scripts can then perform
quick and easy lookups, based on for loops through
numerically indexed arrays, or via instant searching with the
help of string indexes (à la Java hash tables).
As the examples in this chapter demonstrate, the
JavaScript array object features numerous methods to facilitate
managing the data inside an array. It also helps that
JavaScript is loose enough to allow arrays to grow or shrink
as their data requires.
Perhaps the two most important features of JavaScript
arrays to have in your hip pocket are converting arrays to
delimited string objects and sorting. Conversion to strings is
important when you wish to transport data from an array to
another venue that passes only strings, such as passing data
to another page via the URL search string. At the receiving
end, a script converts the search string to an array through
the inverse operation provided by the string.split()
method.
JavaScript’s array sorting feature is remarkably powerful and
flexible. Even if the array consists of objects, you can sort the
array based on values assigned to properties of those objects.
Examples Highlights
✦ Convert an array into a delimited string via the code
shown in Listing 37-7.
✦ To flip the order of an array without resorting to sorting,
see Example 37-8 for the array.reverse() method.
✦ Listing 37-9 demonstrates a few important aspects of the
array.sort() method. In addition to the traditional
alphabetical sorting, one of the sorting functions operates
on the length property of the string object stored
in each entry of the array. Powerful stuff with very little
code.
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C H A P T E R
✦ ✦ ✦ ✦
In This Chapter
Converting an array
to a delimited string
Sorting arrays
Combining arrays
and replacing items
in an array
✦ ✦ ✦ ✦