We already created instances with the simple Rectangle
constructor function. We just needed to use the new
keyword and the constructor function name. We then need to specify the required arguments enclosed in parentheses and assign the result to a variable.
The following lines declare a new version of the Rectangle
constructor function that adds a calculateArea
function to the blueprint:
function Rectangle(width, height) { console.log("I'm creating a new Rectangle"); this.width = width; this.height = height; this.calculateArea = function() { return this.width * this.height; } }
The new constructor function adds a parameterless calculateArea
method to the instance. The following lines of code create a new Rectangle
object named rectangle3
and then print the results of the call to the calculateArea
method for this object:
var rectangle3 = new Rectangle(143, 187); rectangle3.calculateArea();
If we enter the following line, the JavaScript...