Learn Object-Oriented Programming in JavaScript/

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Methods in Constructor Functions

Methods in Constructor Functions

This lesson teaches us how to define and add new methods in a constructor function.

We'll cover the following...

Defining Methods

Methods are defined differently in constructor functions.

Example

We defined our methods inside object literals in the following way:

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Javascript (babel-node)
//creating an object named employee
var employee = {
  //defining properties of the object
  //setting data values
  name : 'Joe',
  age : 28,
  designation : 'Developer',
  //function to display name of the employee
  displayName() {
    console.log("Name is:", this.name)
  }
}
//calling the method
employee.displayName()

Now, let’s write the same function but for the constructor function this time:

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Javascript (babel-node)
//creating an object named Employee
function Employee(_name,_age,_designation) {
   this.name = _name,
   this.age = _age,
   this.designation = _designation,
  //function to display name of the Employee
  this.displayName = function() {
    console.log("Name is:", this.name)
  }
}
//creating an object
var employeeObj = new Employee('Joe',22,'Developer')
//calling the method for employeeObj
employeeObj.displayName()

Explanation

In line 9 of the code for object literal, the method declaration was simple: the name of the function followed by ...