oops

Author: Aeagon07

15_OOPs/notes.md

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+# Javascript and Classes
+
+Yes, Javascript does have classes. But, they are just the syntactic sugar cuase the javscript is prototype-based langauge and it works in existing prototype-based inheritance mechanisms..
+
+## OOP 
+
+## Object
+- Collection of properties and methods
+- toLowerCase
+
+## why use OOP
+- code is getting mess-up (spegaty code)
+- we can use different feature like sevices 
+
+## Parts of OOPs
+Object literal
+
+- Constructor function
+- Protype
+- Classes
+- Instances (new, this)
+
+# 4 Pillors
+- Abstraction -> Hiding details from unneccessary users (e.g., fetch, network calls)
+- Inheritance -> 
+- Encapsulation -> A wrapper 
+- Polymorphism

15_OOPs/oops.js

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+// Object literal  -> Simply an Object
+const user = {
+    username: "Hitesh",
+    loginCount : 8,
+    isLogged : true,
+
+    getUserDetails : function(){
+        // console.log("Got user details hide form you!")
+        console.log(`Username: ${this.username}`)
+        // if we not use it it 
+        // give me an error cause fucntion don't kown what user name is 
+        // although it is define in the scope but it cannont accessing 
+        // that's why we use the this
+        console.log(this) // shows you the current constest or the current object user which is pointed by the this 
+    }
+}
+
+// console.log(user.username)
+// console.log(user.getUserDetails())
+
+// This keyword => it is basically a current contest in the scope
+// you konw that writing this in the global give you empty or in browser gives you the window object  
+
+// Constructor Function  
+
+function UserOne(username, loginCount, isLogged){
+    // this is used with the variable
+    this.username = username;
+    this.loginCount = loginCount;
+    this.isLogged = isLogged
+    
+    return this
+    // return nahi bhi hoga to bhi ye return to hoga cause return is  implecity define
+}
+
+const user1 = UserOne("Hietsh", 12, true);
+// const user2 = UserOne("Chai Aur Code", 11, false) // It overwrite the values that is not the good thing in the code ...
+console.log(user1) // it will show you but, 
+
+// constructor function ik function ki copy deta hai ik instance deta hai uss ka use kar ke duasre koi usse affect nahi hote  
+const user3 = new UserOne("JS", 23, true)
+console.log(user3);
+
+// new working -> if you use new keyword then there is creation of empty object called instance
+// 2) then, construction function call hota hai new keyword ke wajah se ye aapke jitn bhi argument ko wrap karte hai object ke andar
+// 3) this keyword ke andar argument inject ho jate hai 
+
+console.log(UserOne.constructor)
+// it is nothing but the self reference of the any function
+
+// instanceOf 
+console.log(user1 instanceof UserOne) // False -> cause we don't use the new so it not create the instance of the object..
+console.log(user3 instanceof UserOne) // True
+console.log(user3 instanceof Object)  // True