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| 1 | +// JavaScript Classes are templates for JavaScript Objects. |
| 2 | +// ECMAScript 2015, also known as ES6, introduced JavaScript Classes. |
| 3 | + |
| 4 | +// JavaScript Class Syntax |
| 5 | +// Use the keyword class to create a class. |
| 6 | +// Always add a method named constructor(): |
| 7 | + |
| 8 | +// class ClassName { |
| 9 | +// constructor() { ... } |
| 10 | +// } |
| 11 | + |
| 12 | +class Car{ |
| 13 | + constructor(car, year) { |
| 14 | + this.car = car; |
| 15 | + this.year = year; |
| 16 | + } |
| 17 | + age(){ |
| 18 | + const currentYear = new Date().getFullYear(); |
| 19 | + return currentYear - this.year; |
| 20 | + } |
| 21 | +} |
| 22 | + |
| 23 | +let car1 = new Car("Ford", 2014); |
| 24 | +let car2 = new Car("Audi", 2019); |
| 25 | + |
| 26 | +console.log(car1.car); |
| 27 | +console.log(car1.year); |
| 28 | +console.log(car2.car); |
| 29 | +console.log(car2.year); |
| 30 | + |
| 31 | + |
| 32 | +console.log(car1.age()); |
| 33 | + |
| 34 | + |
| 35 | +class Person{ |
| 36 | + constructor(name, village, bdate) { |
| 37 | + this.name = name; |
| 38 | + this.village =village; |
| 39 | + this.bdate = bdate; |
| 40 | + } |
| 41 | + |
| 42 | + calculateAge(){ |
| 43 | + let birthdate = new Date(this.bdate); |
| 44 | + let difftime = Date.now() - birthdate.getTime(); |
| 45 | + let ageDate = new Date(difftime); |
| 46 | + return Math.abs(ageDate.getUTCFullYear() -1970); |
| 47 | + } |
| 48 | +} |
| 49 | + |
| 50 | +let person1 = new Person("Aktauzzaman","Cox's Bazar", "04-13-1998"); |
| 51 | +console.log(person1.bdate); |
| 52 | +console.log(person1.name); |
| 53 | +console.log(person1.calculateAge()); |
| 54 | + |
| 55 | + |
| 56 | +console.log("Examine: "); |
| 57 | +let bdate = "04-13-1998"; |
| 58 | +let birthdate = new Date(bdate); |
| 59 | + |
| 60 | +let difftime = Date.now() - birthdate.getTime(); |
| 61 | +//If assume current year is Sep, 2024. 1970 to 2024 = > 54 years |
| 62 | +// If assume birthdate is Aprinl, 1998. 1970 to 1998 => 28 years |
| 63 | +// 54-28 = 26 years |
| 64 | +let ageDate = new Date(difftime); // this function add 26 years equal ms |
| 65 | +// to 1970 that will be = 1996 |
| 66 | +console.log(Math.abs(ageDate.getUTCFullYear() -1970)); // 1996-1970 = 26 |
| 67 | + |
| 68 | + |
| 69 | +// JavaScript Class Inheritance |
| 70 | +// To create a class inheritance, use the extends keyword. |
| 71 | +// A class created with a class inheritance inherits all the methods from another class: |
| 72 | + |
| 73 | +class Person1{ |
| 74 | + constructor(fname, lname){ |
| 75 | + this.fname = fname; |
| 76 | + this.lname = lname; |
| 77 | + } |
| 78 | + |
| 79 | + getFullName(){ |
| 80 | + return this.fname + ' ' + this.lname; |
| 81 | + } |
| 82 | + |
| 83 | + greet(){ |
| 84 | + console.log(`Hello, ${this.getFullName()}`); |
| 85 | + } |
| 86 | +} |
| 87 | + |
| 88 | + |
| 89 | +let p1 = new Person1("Abdullah", "Abdur Rahman"); |
| 90 | +p1.greet(); |
| 91 | + |
| 92 | +class Customer extends Person1{ |
| 93 | + constructor(fname, lname, cusId, address){ |
| 94 | + super(fname,lname); |
| 95 | + this.cusId = cusId; |
| 96 | + this.address = address; |
| 97 | + } |
| 98 | + getCustInfo(){ |
| 99 | + console.log("\tCustomer Ifo:"); |
| 100 | + console.log("Name:", this.getFullName()); |
| 101 | + console.log("Customer Id:", this.cusId); |
| 102 | + console.log("Address:", this.address); |
| 103 | + } |
| 104 | +} |
| 105 | + |
| 106 | + |
| 107 | +p2 = new Customer("Akib", "Zabed", 123, "Dhaka"); |
| 108 | +p2.getCustInfo(); |
| 109 | + |
| 110 | +// The super() method refers to the parent class. |
| 111 | +// By calling the super() method in the constructor method, we call the parent's constructor method and gets access to the parent's properties and methods. |
| 112 | + |
| 113 | +// Unlike functions, and other JavaScript declarations, class declarations are not hoisted. |
| 114 | +// That means that you must declare a class before you can use it: |
| 115 | + |
| 116 | +// const myCar = new Car1("Ford") //cause error |
| 117 | + |
| 118 | +class Car1 { |
| 119 | + constructor(brand) { |
| 120 | + this.carname = brand; |
| 121 | + } |
| 122 | + } |
| 123 | + |
| 124 | + //Now you can use the class: |
| 125 | + const myCar = new Car1("Ford") |
| 126 | + console.log(myCar.carname); |
| 127 | + |
| 128 | +// Static Function |
| 129 | + |
| 130 | +// Static class methods are defined on the class itself. |
| 131 | +// You cannot call a static method on an object, only on an object class. |
| 132 | +class P{ |
| 133 | + constructor(fname,lname) { |
| 134 | + this.fname = fname; |
| 135 | + this.lname = lname; |
| 136 | + } |
| 137 | + static hello() { |
| 138 | + return "Hello!!"; |
| 139 | + } |
| 140 | + |
| 141 | + getFullName(){ |
| 142 | + return this.fname + ' ' + this.lname; |
| 143 | + } |
| 144 | +} |
| 145 | + |
| 146 | +let ob1 = new P("Abdullah", "Abdur Rahman"); |
| 147 | +console.log(P.hello()); |
| 148 | +console.log(ob1.getFullName()); |
| 149 | +// ob1.hello();//Error |
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