Course Content
Object-Oriented Programming in JavaScript
Object-Oriented Programming in JavaScript
Overriding
Overriding Methods
In the previous chapter, we redefined the constructor for the daughter class. If there are some methods in the parent class that you want to be different in the daughter’s, you can simply write it again with another function's body:
Here, if you rotate the square, nothing changes, so we'll override this function to only output the message, not change the sides.
In case if you want to use methods from parent’s class, use super keyword again. Let's use increase() method from Rectangle class inside increaseTwice() from Square class.
Task
Let's place our Figures in the boxes. Add to the parent's class function box(), which outputs the message I am a Rectangle, and I need a box of size won h, where w and h are width and height of the current Rectangle. Then override this function in Square class, so it outputs the message: I am a Square, and I need a box of size son s, and s is a length of square's side.
Create Rectangle and Square objects and call box() method for them.
Task
Let's place our Figures in the boxes. Add to the parent's class function box(), which outputs the message I am a Rectangle, and I need a box of size won h, where w and h are width and height of the current Rectangle. Then override this function in Square class, so it outputs the message: I am a Square, and I need a box of size son s, and s is a length of square's side.
Create Rectangle and Square objects and call box() method for them.
Overriding attributes
Inside the daughter's class, we can refer to any attributes and methods of the parent's class. In general, there is no sense to override attributes because you can refer them directly from the parent's class. The exception is private attributes: they are accessible only inside the current class, that's why you can't override them.
Everything was clear?
Overriding
Overriding Methods
In the previous chapter, we redefined the constructor for the daughter class. If there are some methods in the parent class that you want to be different in the daughter’s, you can simply write it again with another function's body:
Here, if you rotate the square, nothing changes, so we'll override this function to only output the message, not change the sides.
In case if you want to use methods from parent’s class, use super keyword again. Let's use increase() method from Rectangle class inside increaseTwice() from Square class.
Task
Let's place our Figures in the boxes. Add to the parent's class function box(), which outputs the message I am a Rectangle, and I need a box of size won h, where w and h are width and height of the current Rectangle. Then override this function in Square class, so it outputs the message: I am a Square, and I need a box of size son s, and s is a length of square's side.
Create Rectangle and Square objects and call box() method for them.
Task
Let's place our Figures in the boxes. Add to the parent's class function box(), which outputs the message I am a Rectangle, and I need a box of size won h, where w and h are width and height of the current Rectangle. Then override this function in Square class, so it outputs the message: I am a Square, and I need a box of size son s, and s is a length of square's side.
Create Rectangle and Square objects and call box() method for them.
Overriding attributes
Inside the daughter's class, we can refer to any attributes and methods of the parent's class. In general, there is no sense to override attributes because you can refer them directly from the parent's class. The exception is private attributes: they are accessible only inside the current class, that's why you can't override them.
Everything was clear?
Overriding
Overriding Methods
In the previous chapter, we redefined the constructor for the daughter class. If there are some methods in the parent class that you want to be different in the daughter’s, you can simply write it again with another function's body:
Here, if you rotate the square, nothing changes, so we'll override this function to only output the message, not change the sides.
In case if you want to use methods from parent’s class, use super keyword again. Let's use increase() method from Rectangle class inside increaseTwice() from Square class.
Task
Let's place our Figures in the boxes. Add to the parent's class function box(), which outputs the message I am a Rectangle, and I need a box of size won h, where w and h are width and height of the current Rectangle. Then override this function in Square class, so it outputs the message: I am a Square, and I need a box of size son s, and s is a length of square's side.
Create Rectangle and Square objects and call box() method for them.
Task
Let's place our Figures in the boxes. Add to the parent's class function box(), which outputs the message I am a Rectangle, and I need a box of size won h, where w and h are width and height of the current Rectangle. Then override this function in Square class, so it outputs the message: I am a Square, and I need a box of size son s, and s is a length of square's side.
Create Rectangle and Square objects and call box() method for them.
Overriding attributes
Inside the daughter's class, we can refer to any attributes and methods of the parent's class. In general, there is no sense to override attributes because you can refer them directly from the parent's class. The exception is private attributes: they are accessible only inside the current class, that's why you can't override them.
Everything was clear?
Overriding Methods
In the previous chapter, we redefined the constructor for the daughter class. If there are some methods in the parent class that you want to be different in the daughter’s, you can simply write it again with another function's body:
Here, if you rotate the square, nothing changes, so we'll override this function to only output the message, not change the sides.
In case if you want to use methods from parent’s class, use super keyword again. Let's use increase() method from Rectangle class inside increaseTwice() from Square class.
Task
Let's place our Figures in the boxes. Add to the parent's class function box(), which outputs the message I am a Rectangle, and I need a box of size won h, where w and h are width and height of the current Rectangle. Then override this function in Square class, so it outputs the message: I am a Square, and I need a box of size son s, and s is a length of square's side.
Create Rectangle and Square objects and call box() method for them.
Overriding attributes
Inside the daughter's class, we can refer to any attributes and methods of the parent's class. In general, there is no sense to override attributes because you can refer them directly from the parent's class. The exception is private attributes: they are accessible only inside the current class, that's why you can't override them.
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