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C # tutorial
ECMAScript 2015, also known as ES6, introduced JavaScript Classes
Use the keyword class to create a class.
Always add a method named constructor():
class ClassName {
constructor() { ... }
}
class Car {
constructor(name, year) {
this.name = name;
this.year = year;
}
}
The example above creates a class named "Car".
The class has two initial properties: "name" and "year".
A JavaScript class is not an object.
It is a template for JavaScript objects.
When you have a class, you can use the class to create objects:
The example above uses the Car class to create two Car objects.
The constructor method is called automatically when a new object is created.
The constructor method is a special method:
If you do not define a constructor method, JavaScript will add an empty constructor method.
Class methods are created with the same syntax as object methods.
Use the keyword class to create a class.
Always add a constructor() method.
Then add any number of methods.
class ClassName {
constructor() { ... }
method_1() { ... }
method_2() { ... }
method_3() { ... }
}
Create a Class method named "age", that returns the Car age:
class Car {
constructor(name, year) {
this.name = name;
this.year = year;
}
age() {
let date = new Date();
return date.getFullYear() - this.year;
}
}
let myCar = new Car("Ford", 2014);
document.getElementById("demo").innerHTML =
"My car is " + myCar.age() + " years old.";
You can send parameters to Class methods:
class Car {
constructor(name, year) {
this.name = name;
this.year = year;
}
age(x) {
return x - this.year;
}
}
let date = new Date();
let year = date.getFullYear();
let myCar = new
Car("Ford", 2014);
document.getElementById("demo").innerHTML=
"My car is
" + myCar.age(year) + " years old.";
table.browserref { border-collapse:collapse;width:100%; } table.browserref th:first-child,table.browserref td:first-child{padding-left:16px} table.browserref th{ height:32px;background-repeat:no-repeat;background-position:center center;font-weight:normal;padding:11px 5px 11px 5px;vertical-align:middle; } table.browserref .bsChrome {background-image:url('/images/compatible_chrome.png');} table.browserref .bsEdge {background-image:url('/images/compatible_edge.png');} table.browserref .bsFirefox {background-image:url('/images/compatible_firefox.png')} table.browserref .bsSafari {background-image:url('/images/compatible_safari.png');} table.browserref .bsOpera {background-image:url('/images/compatible_opera.png')} table.browserref td{ text-align:center;padding:8px;vertical-align:top; }
The following table defines the first browser version with full support for Classes in JavaScript:
| Chrome 49 | Edge 12 | Firefox 45 | Safari 9 | Opera 36 |
| Mar, 2016 | Jul, 2015 | Mar, 2016 | Oct, 2015 | Mar, 2016 |
You will learn a lot more about JavaScript Classes later in this tutorial.