Programming Tutorials

(追記) (追記ここまで)

prototype in JavaScript

By: Tanya in Javascript Tutorials on 2023年04月26日 [フレーム]

In JavaScript, every object has a prototype. A prototype is an object that is used as a template for creating new objects. When an object is created, it inherits properties and methods from its prototype.

The prototype is accessible through the prototype property of a constructor function. When a function is used as a constructor to create an object with the new keyword, the new object's prototype is set to the prototype of the constructor function.

Here is an example:

function Person(name) {
 this.name = name;
}
Person.prototype.sayHello = function() {
 console.log("Hello, my name is " + this.name);
};
var john = new Person("John");
john.sayHello(); // logs "Hello, my name is John"

In this example, the Person function is used as a constructor to create a new object john. The sayHello method is added to the Person prototype object. When john.sayHello() is called, the sayHello method is looked up in the john object's prototype chain, and since it is not found in the john object itself, it is found in the Person prototype object and executed.

The prototype chain can be used to implement inheritance in JavaScript. Inheritance allows objects to inherit properties and methods from their prototypes. This can be useful for creating classes of objects with similar behavior.

Previous
<< => in JavaScript

Next
map() in JavaScript>>

(追記) (追記ここまで)