check null values in JavaScript

What is ‘this’ in JavaScript?

Hello everyone, today's I am going to share a basic and very confusing concepts that is called 'this' keyword :)
The 'this' keyword behaves a little differently in JavaScript compared to other languages.
In most of the other languages, 'this' keyword is a reference to the current object instantiated by the classes and methods. 
In the JavaScript languages, 'this' keyword refers to the object which 'owns' the method, but it depends on how a function is called.
The examples in details as given below.
//Global Scope in JavaScript
//In the below example, ‘this’ keyword refers to the global object.

window.sms = "Hi, I am window object";

console.log(window.sms);
console.log(this.sms); // Hi, I am window object.
console.log(window === this); // Its return true.

//Calling a Function in JavaScript 
//In the below example, ‘this’ keyword remains the global object if we are calling a function.

window.sms = "Hi, I am window object";

// Creating a function
function thisMethod() {
    console.log(this.sms); // Hi, I am window object.
    console.log(window === this); //Its return true.
}

// Calling a function
thisMethod();

//Calling Object Methods in JavaScript
//In the below example, when we calling an object constructor or any of its methods, 
//‘this’ keyword refers to the instance of the object.

window.sms = "Hi, I am window object";

function objectTestMethod() {
    this.sms = "Hi, I am a test object.";
    this.method1 = function () {
        console.log(this.sms); // Hi, I am a test object.
    };
}

objectTestMethod.prototype. method2 = function () {
    console.log(this.sms); // Hi, I am a test object.
};

// Creating object and calling methods

var v = new objectTestMethod();
v. method1();
v. method2();

ANIL SINGH

Anil Singh is an author, tech blogger, and software programmer. Book writing, tech blogging is something do extra and Anil love doing it. For more detail, kindly refer to this link..
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