JavaScript 2.0-The Complete Reference, Second ... - freecodingtutorial

In addition to the direct way elements may be accessed, JavaScript‘s for/in construct is perfect
for iterating over the elements of associative arrays. The following example loops through all
elements of an array and prints them out:
var customers = new Object();
customers["Tom Doe"] = "123 Main St., Metropolis, USA";
customers["Sylvia Cheung"] = "123 Fake St., Vancouver B.C., Canada";
customers["George Speight"] = "145 Baldwin St., Dunedin, NZ";
for (var client in customers)
{
}
document.writeln("The address of client " + client + " is:");
document.writeln(customers[client]);
document.writeln("");
Each name that has data associated with it is assigned to client, one at a time. This variable is
used to access the data in the array. The output of the previous example is shown in Figure 6-
4.
Figure 6-4: Associative arrays provide key/value data lookup capabilities in JavaScript.
Now that we‘ve covered the fundamentals of how objects behave and how you can create and
manipulate generic objects, it‘s time to explore JavaScript‘s object-oriented features. These
features enable you to structure your scripts in a mature fashion similar to more mainstream
application development languages such Java and C++. JavaScript‘s object-oriented features
aren‘t as flexible as these languages, but you‘ll probably find that what JavaScript has to offer is
well suited to the kinds of tasks required when writing large scripts or building Web-based
applications.