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just like object templateconstructor function is different from object propertiesconstructor function: this.title = ‘aaaa’ (default value)object property: title: ‘aaaa’DO NOT return any value in a constructor functionthe ‘new’ synctax already create a new object and return itself
it does not look whether it is created first or not.EVEN THE OBJECT AND METHODS WERE CREATED FIRST, if we add a new method to the instance later, it will use the latter.The same for PROPERTY: it will look for value in the instance first, before going up to the prototypeEVEN WHEN YOU CHANGE PRIMITIVE (default) FUNCTION
strings, numbers, arrays are also objectsand they have default / primitive methods / 1st-level prototypejust to clarify how other / normal objects are affected by our custom default methodstring can be used as an Array Object or Normal Object
instead of creating a function and validate data before setting to a variablemanipulate input and output data behind the scene
do not need to store fullName when we already have firstName and lastNamejust need to calculate with a getter functionthe same for setter function (but actually setter is only useful when we use with getter)
when you have a function that require many input / arguments from an object
youhoc
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Advanced Objects & Methods
Definition
Create an object
Just like a JSON object ha...
Constructor Function
What if I want to add another book?
Use constructor function to create new objects
Setting up Prototype Object
Shared Methods (functions) between Instance Objects
Remeber to use this and DO NOT USE arrow function
Please note an important use case regarding variable scope
Prototypal Inheritance
The instance look for property and methods inside itself first, before looking up to the prototype.
Primitives & Objects
There are many default methods and functions related to objects
WHY WE CAN USE A METHOD BUT IT DOES NOT EXIST?
Because...
'hasOwnProperty' mean a property at object level, not higher level
You can even create a new default Object method, and use everywhere
Different synctax for new objects
Primitives for special Objects
myArray — Array.Prototype — Object.prototype — null
myFunction — Function.prototype — Object.prototype — null
myNumber — Number.prototype — Object.prototype — null
myString — String.protoype — Object.prototype — null
Class Syntax
class = constructor function + prototype methods
IMPORTANT: no comma , between contructor and method names in class
Subclass
Person → Employee, Student
Book → Paper Book, Podcast Book
Getter & Setter
Get correct data type with validation
Use getter and setter in class
THIS IS USEFUL TO REPLACE AUTOMATIC METHODS WITH PROPERTY
De-structuring
Closures
Run a function to create (return) a function
This is useful to manipulate objects
Advanced Synctax
Shorthand Synctax for Object Properties
If object properties are the same as variables, you can use:
Destructuring Synctax for Object Properties
Convert object properties into variables quickly, using the same property names:
Applications for Destructuring
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