Update: added new files

Author: isinghabhishek

JavaScript Part-01/75CreateFunctionsToCreateMultipleObjects.js

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+//  creating functions to create  multiple objects
+
+//  proto ,  prottype ,   class --> will learn later
+
+//  normal way
+// const user = {
+//     firstName: "Abhishek",
+//     lastName: "Singh",
+//     email: "singhabhishek@gmail.com",
+//     age: 18,
+//     address: "House Number, Colony, pincode, state",
+//     about: function(){
+//         return `${this.firstName} is ${this.age} years old.`;
+//     },
+//     is18: function(){
+//         return this.age >= 18;
+//     }
+// }
+// const aboutUser = user1.about();
+// console.log(aboutUser);
+
+
+//  what if we needs millons of the user data then what we will do
+//  hum bar bar user ki data ko input to nahi karenge so that's why 
+//  we will create function which will take user info data as inputs
+
+// these is best way
+
+//  1).  function(that function create object)
+//  2).  add key value pair
+//  3).  object ko return krega
+
+function createUser(firstName, lastName, email, age, address){
+    const user = {}; 
+    user.firstName = firstName;
+    user.lastName = lastName;
+    user.email = email;
+    user.age = age;
+    user.address = address;
+    user.about = function(){
+        return `${this.firstName} is ${this.age} years old.`;
+    }
+    user.is18 = function(){
+        return this.age >= 18;
+    }
+    return user;
+}
+
+const user1 = createUser('Abhishek', 'Singh', 'singh@gmail.com', '18', 'Mirzapur uttar pradesh');
+console.log(user1);
+
+const is18 = user1.is18();
+console.log(is18); // true
+
+const about = user1.about();
+console.log(about); // Abhishek is 18 year old.
+
+// in these approach also have so setback(kameeyaa bhut hai esh me)
+// so will keep inproving it in next file(76).

JavaScript Part-01/76Extended75.js

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+//  jethne bar user banegga uthe ni baar  methods banegaa our 
+//  hamare memory me uthni he methods store honge
+// user1 object banega usme bhi 'about' & 'is18' method honge
+// user2 object banega usme bhi 'about' & 'is18' method honge
+// user3 object banega usme bhi 'about' & 'is18' method honge
+// these is setback that we need to optimize
+//  suppose ke 1 millon user hai to 1 million baar methods bhi store honge
+//  memory me our memor jade use hoge we need to optimize it
+//  we need only one copy of methods
+//  javascript store it's references type
+
+
+// userMethod kar ke object create kar lenge
+// har object ke liye same hai methods
+// ek objects ke andar in methods ko store kar lenge
+// hum ek copy banake rakh lenge ur ush ko use karenge
+const userMethods = {
+    about: function(){
+        return `${this.firstName} is ${this.age} years old.`;
+    },
+    is18: function(){
+        return this.age >= 18;
+    }    
+}
+function createUser(firstName, lastName, email, age, address){
+    const user = {};
+    user.firstName = firstName;
+    user.lastName = lastName;
+    user.email = email;
+    user.age = age;
+    user.address = address;
+    // creating the referencs(address) of the 'about' & 'is18' function
+    user.about = userMethods.about;
+    user.is18 = userMethods.is18;
+    return user;
+}
+
+const user1 = createUser('Abhishek', 'Singh', 'singh@gmail.com', '18', 'Mirzapur uttar pradesh');
+const user2 = createUser('Abimaniyu', 'dev', 'singh@gmail.com', '16', 'prayagraj uttar pradesh');
+const user3 = createUser('prithivi', 'chauhan', 'singh@gmail.com', '24', 'varanasi uttar pradesh');
+const user4 = createUser('Raaj', 'Rajput', 'singh@gmail.com', '14', 'Delhi ');
+
+console.log(user2.about());
+console.log(user4.about());
+
+// in these code also have some kameeyaa we need to improve
+// need to optimize it improveing our code

JavaScript Part-01/77Extended76.js

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+
+// we improveing our code so that it takes less memory
+// suppose we want to add thousands of the method
+// and what if we forget to add it's reference in javascript
+// so, first we will understand in file "78.js"
+
+const userMethods = {
+    about: function(){
+        return `${this.firstName} is ${this.age} years old.`;
+    },
+    is18: function(){
+        return this.age >= 18;
+    },
+    sing: function(){
+        return 'sa re ga ma....';
+    }    
+}
+function createUser(firstName, lastName, email, age, address){
+    // using Object.create() function, these helps
+    // in setting up the "userMethods" in "__proto__". 
+    // "__proto__" references hai "userMethods" kaa
+    const user = Object.create(userMethods); // this line set "userMethod" in "__proto__" // understand in file 78
+    user.firstName = firstName;
+    user.lastName = lastName;
+    user.email = email;
+    user.age = age;
+    user.address = address;
+    user.about = userMethods.about;
+    user.is18 = userMethods.is18;
+    user.sing = userMethods.sing;
+    return user;
+}
+
+const user1 = createUser('Abhishek', 'Singh', 'singh@gmail.com', '18', 'Mirzapur uttar pradesh');
+const user2 = createUser('Abimaniyu', 'dev', 'singh@gmail.com', '16', 'prayagraj uttar pradesh');
+const user3 = createUser('prithivi', 'chauhan', 'singh@gmail.com', '24', 'varanasi uttar pradesh');
+const user4 = createUser('Raaj', 'Rajput', 'singh@gmail.com', '14', 'Delhi ');
+
+console.log(user2)
+console.log(user2.about());
+// user methods  are set in [[prototype]] or __proto__
+//  "__proto__" me "userMethods" set hojaye gaa
+//   "__proto__" is reference of "userMethod" Object.
+
+//   if we create thousand of the userMethods objects 
+//  and that are not persent in the "userCreate" object than
+//  JavaScript will automatically will access that object 
+//  from '__proto__' which  contents all that objects that are not in 
+
+console.log(user4.about());
+console.log(user3.sing());

JavaScript Part-01/78.js

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+
+const obj1 = {
+    key1: "value1",
+    key2: "value2"
+}
+// const obj2 = {
+//     key3: "value3"
+// }
+// console.log(obj2.key3);  // o/p--> value3
+// console.log(obj2.key1);  // o/p--> undefined
+
+//  we want that javascript ko agar obj2 me 'key1' naa mile tho oo 
+//  khud 'obj1' ke paas jaye ohaa pee dekhe ki 'obj1' me 'key1' hai ke nahi hai to hume dede
+//  khud 'obj1' ke pass jaye oha pe dekhe ki 'key1' hai to muje de de
+
+
+//   "__proto__"
+
+//  offcial ecmascript documentation
+
+//  "[[prototype]]"
+
+// "__proto__"  ,  "[[prototype]]"  --> both are same
+
+//  __proto__ ki madth se javaScript jo cheese 'obj2' 
+//  me nahi ho tho wo usko 'obj1' se lelega bcz 'obj1' is stored in "[[prototype]]"
+
+//  "prototype"  -->  this is diffrent from above two
+
+//  there is one more way to creat empty Object
+//  Object.create(); 
+const obj2 = Object.create(obj1);  //  o/p--> {} 
+// phale javaScript obj2 me dekhe ga agar wohaa pe hai ya nahi key
+// to wo ushko pher wshko obj1 me dekhe ga
+//  Object.create(); 
+//  this helps in stabiliting the connection b/w 'obj1' & 'obj2'. 
+//  this helps in creating 'obj1' properties in the 'obj2', 
+// with help of javaScript "[[prototype]]" object 
+//  JavaScript  ko jo chej 'obj2' se nahi mili to usne use 'obj1' se leli.
+
+obj2.key3 = "value3";
+// obj.key2 = "uniqueKey";
+console.log(obj2.key2); //op--> value2
+
+console.log(obj2);
+// o/p--> key3: "value3"
+//        [[Prototype]]: Object
+
+
+//  this is happening
+console.log(obj2.__proto__);  //  'obj2' ko proto 'obj1' ho gaya
+//  'obj2' ko proto 'obj1' ho gaya with help of Object.create() function
+// const obj2 = Object.create(obj1);
+// o/p--> key1: "value1"
+//        key2: "value2"
+//        [[Prototype]]: Object
+
+//  JavaScript  ko jo chej  'obj2' se nahi mili usne usko "__proto__" or "[[prototype]]"  se leli jahaa pe obj1 stored hai.
+
+// abhi humne bat ki __proto__ ki jishko documentation mein [[prototype]] 
+// likha hua hai broweser ke console mei __proto__ bhi likha 
+// ho saktha hai aur [[prototype]] bhi likha ho sakta hai
+// javaScript mai ek prototype property alag se bhi hoti hai 
+// uske barein mai detail mei baat krenge