JavaScript's prototype system is a form of inheritance, enabling objects to inherit properties and methods from other objects. This characteristic makes JavaScript a prototype-based language, as opposed to a class-based one.
In JavaScript, everything is an object, and every object has a prototype. Prototypes themselves can also have prototypes, creating a chain. When you access a property on an object, JavaScript first checks if the object itself has that property. If not, it looks in the object's prototype. This process continues up the prototype chain until the property is found or the end of the chain is reached. This mechanism is known as prototype chaining.
JavaScript classes are essentially objects that utilize prototypes, providing syntactic sugar over the prototype system. You can also add properties and methods directly to an object's prototype, avoiding the need to define them all within the class. This direct approach can be more memory-efficient, especially when creating numerous instances.
function Person(name) {
this.name = name;
}
Person.prototype.greet = function() {
console.log(`Hello, my name is ${this.name}`);
};
With the introduction of classes in modern JavaScript, method definitions are automatically assigned to the prototype.
class Person {
constructor(name) {
this.name = name;
}
greet() {
console.log(`Hello, my name is ${this.name}`);
}
}