Explain "this" keyword

The "this" keyword in JavaScript refers to the object that the function is a method of. It is a reference to the current execution context and can be used to access properties and methods of the object.

For example, if we have an object called "person" with properties "name" and "age", we can use the "this" keyword to refer to those properties within a method of the object:

const person = {
  name: "John",
  age: 30,
  sayHello: function() {
    return "Hello, my name is " + this.name + " and I am " + this.age + " years old.";
  }
};

console.log(person.sayHello()); // Output: "Hello, my name is John and I am 30 years old."

In the above example, the "sayHello" method uses the "this" keyword to access the "name" and "age" properties of the "person" object.

It's important to note that the value of "this" depends on how the function is called. If the function is called as a method of an object, "this" refers to that object. However, if the function is called without an object context, "this" refers to the global object (in a browser environment, this is usually the window object).