• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

Chapter 8. Objects > Constructors

8.2. Constructors

We saw previously that you can create and initialize a new object in JavaScript by using the new operator in conjunction with a predefined constructor function such as Object( ), Date( ), or Function( ). These predefined constructors and the built-in object types they create are useful in many instances. However, in object-oriented programming, it is also common to work with custom object types defined by your program. For example, if you are writing a program that manipulates rectangles, you might want to represent rectangles with a special type, or class, of object. Each object of this Rectangle class would have a width property and a height property, since those are the essential defining characteristics of rectangles.

To create objects with properties such as width and height already defined, we need to write a constructor to create and initialize these properties in a new object. A constructor is a JavaScript function with two special features:


PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint