02 Basics / 03 Objects JS

Learned about Object in JS and Object literals and constructors, How to declare object, accessing object, changing values of keys, adding functions, symbols, arrays in Object.

Author: aayushyadavz

02_Basics/03_objects.js

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+/* 3. Objects
+
+Note: When objects are declared as literals then singletons are not made,
+When objects are declared as constructors then singletons are made.
+
+Object through constructor method, */
+Object.create
+
+// And now we will discuss about Object literals below,
+
+const mySym = Symbol("key1") // Declaring a Symbol.
+
+const jsUser = {
+    name: "Ayush", /* In this name (key) is treated as string ("name") in system & "Ayush"
+    is it's value. */
+    "full name": "Ayush Yadav",
+    [mySym]: "myKey1", // refering that above declared Symbol as objects key using [].
+    age: 21,
+    loctaion: "Azamgarh",
+    email: "ayushyadav@gmail.com",
+    isLoggedIn: false,
+    lastLoggedInDays: ["Monday", "Tuesday", "Thursday"] // Array as value.
+    // We can also give objects as values.
+}
+// Accessing Objects,
+console.log(jsUser.email); // Output: ayushyadav@gmail.com | Not the best way to access.
+console.log(jsUser["email"]); /* Output: ayushyadav@gmail.com | Using "" cause this key 
+(email) is treated as strings behind the screen. */
+console.log(jsUser["full name"]); /* Output: Ayush Yadav 
+Note: It's not possible to access it like this (console.log(jsUser.full name)) */
+console.log(jsUser[mySym]); /* Acessing that symbol used as key in Object.
+
+--------------------------------------------------------------------------------------------
+Changing Values, */
+jsUser.email = "ayushyadav@google.com"
+// Freezing values so that it can't be changed,
+// Object.freeze(jsUser)
+jsUser.email = "ayushyadav@microsoft.com"
+console.log(jsUser); /* value will not change to "ayushyadav@microsoft.com" cause we have 
+freezed the object. 
+
+---------------------------------------------------------------------------------------------
+Adding Functions in Object, */
+jsUser.greetings = function () {
+    console.log("Hi JS user");
+}
+
+jsUser.greetings2 = function() {
+    console.log(`Hi JS user, ${this.name}`); // Refering name key from the Object. 
+}
+
+console.log(jsUser.greetings()); // Output: Hi JS user
+console.log(jsUser.greetings2()); // Output: Hi JS user, Ayush