Training Guide: Programming in HTML5 with JavaScript and CSS3 Ebook

268 CHAPTER 6 Essential JavaScript and jQuery

FIGURE 6-2 he failing test assertions after a second vehicle is usedT

To solve the problem, you want to implement encapsulation. Then you need to create

objects, each with its own data. To implement encapsulation, use the var keyword for the

year, make, and model. This will make these variables private to the function. Notice that the

var keyword is not used with getInfo because the getInfo variable needs to be public to be

called from outside the object, but you don’t want the getInfo variable to be global. Assign

getInfo to the current object by using the this keyword. The result is a class that encapsulates

the data and exposes getInfo to retrieve the data in a controlled way as follows.

function Vehicle(theYear, theMake, theModel) {

var year = theYear;

var make = theMake;

var model = theModel;

this.getInfo = function () {

return 'Vehicle: ' + year + ' ' + make + ' ' + model;

};

}

IMPORTANT PRIVATE DATA ISN’T SECURE

In object-oriented programming, private data is not intended to be secure. Private data

provides encapsulation so the details can be hidden; the user sees only what is necessary

and isn’t bogged down in the details.