When working with JavaScript, it is common to use constructor functions to create objects. Constructor functions are used to initialize object properties and set up methods that can be accessed by instances of the object.

To access properties and methods defined in a constructor function, we need to create an instance of the object using the new keyword. Let’s look at an example:

Example

function Person(name, age) {
  this.name = name;
  this.age = age;

  this.greet = function() {
    console.log(`Hello, my name is ${this.name}`);
  };
}

// Creating an instance of the Person object
var john = new Person("John", 30);

// Accessing properties
console.log(john.name); // Output: John
console.log(john.age); // Output: 30

// Accessing methods
john.greet(); // Output: Hello, my name is John

In the example above, we have a constructor function Person that takes two parameters name and age. Inside the constructor function, we set the name and age properties of the object using this.name and this.age.

We also define a greet method that can be accessed by instances of the Person object. It uses the this.name property to greet the person by name.

To create an instance of the Person object, we use the new keyword followed by the name of the constructor function and pass the required parameters.

We can then access the properties and methods of the instance using dot notation. In the example, we access the name and age properties using john.name and john.age, and we call the greet method using john.greet().

By using the new keyword to create instances of a constructor function, we can access the properties and methods defined in the constructor. This allows us to create reusable objects with shared behavior and attributes.