function in class javascript code example

Example 1: javascript class

class ClassMates{
	constructor(name,age){
    	this.name=name;
      	this.age=age;
    }
  	displayInfo(){
    	return this.name + "is " + this.age + " years old!";
    }
}

let classmate = new ClassMates("Mike Will",15);
classmate.displayInfo();  // result: Mike Will is 15 years old!

Example 2: javascript new function as class

// Javascript Function that behaves as class, with private variables
function Person(name){
    const birth = new Date();
    this.greet = () => `Hello my name is ${name}. I was born at ${birth.toISOString()}`;
}

const joe = new Person("Joe");
joe.greet(); // Hello my name is Joe. I was born at 2021-04-09T21:12:33.098Z
// The birth variable is "inaccessible" from outside so "private"

Example 3: javascript class

//JavaScript class: Here a quick code example

// Basic class
class Rectangle {
  
  // Constructor
  constructor(height, width) {
    // Member variables
    this.height = height;
    this.width = width;

    // Access static member variable
    Rectangle.count++;
  }
  
  // Getter
  get area() {
    return this.calcArea();
  }
  
  // Method
  calcArea() {
    return this.height * this.width;
  }

  // Static method
  static calcArea(width, height) {
    return width * height;
  }
}

// Static member variable
Rectangle.count = 0;


// Class instantiation
const square = new Rectangle(10, 10);

// Access member variable
console.log(square.height, square.width); // 10 10

// Call getter
console.log(square.area);	// 100

// Call method
console.log(square.calcArea()); // 100


// Access static member variable
console.log(Rectangle.count); // 1

// Call static method
console.log(Rectangle.calcArea(15, 15));  // 225

Example 4: javascript class example

// to create a class named 'LoremIpsum':

class LoremIpsum {
  
  // a function that will be called on each instance of the class
  // the parameters are the ones passed in the instantiation

  constructor(a, b, c) {
    this.propertyA = a;
    
    // you can define default values that way
    this.propertyB = b || "a default value";
    this.propertyC = c || "another default value";
  }
  
  // a function that can influence the object properties
  
  someMethod (d) {
    this.propertyA = this.propertyB;
    this.propertyB = d;
  }
}






// you can then call it
var loremIpsum = new LoremIpsum ("dolor", null, "sed");

// at this point:
// loremIpsum = { propertyA: 'dolor',
//                propertyB: 'a default value',
//                propertyC: 'sed' }

loremIpsum.someMethod("amit");

// at this point:
// loremIpsum = { propertyA: 'a default value',
//                propertyB: 'amit',
//                propertyC: 'sed' }







.

Example 5: javascript classes

let Person = class {
  constructor(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }
}