What is the difference between prototype and prototype chain

The difference between prototype and prototype chain is: 1. Prototype is an attribute that each object has, including some shared attributes and methods, which is used to realize the sharing and inheritance of attributes and methods between objects. The prototype chain is a mechanism that implements inheritance through the prototype relationship between objects. It defines the inheritance relationship between objects so that objects can share the properties and methods of the prototype object; 2. The function of the prototype is to define the shared properties of the object. and methods, so that multiple objects can share the properties and methods of the same prototype object, and the function of the prototype chain is to realize the inheritance relationship between objects, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Prototype and prototype chain are important concepts in JavaScript and are used to implement prototype-based inheritance. Below I will introduce the meaning and difference of prototype and prototype chain in detail.

1. Prototype:

In JavaScript, each object has a prototype. The prototype is an object that contains some shared properties and methods. When we create an object, JavaScript automatically associates a prototype with the object.

We can create a new object through the `Object.create()` method and set its prototype to the specified object. For example:

var person = {
  name: '张三',
  age: 20,
  greet: function() {
    console.log('你好，我是' + this.name);
  }
};
var student = Object.create(person);
student.grade = '一年级';

In the above example, the `person` object is the prototype of the `student` object. The `student` object inherits the properties and methods of the `person` object.

2. Prototype Chain:

The prototype chain is a mechanism that implements inheritance through the prototype relationship between objects. When we access a property or method of an object, if the object itself does not have this property or method, JavaScript will look up along the prototype chain until it finds the property or method or reaches the end of the prototype chain (i.e. `Object.prototype`) until.

For example, we can call the `greet` method through the `student` object:

student.greet(); // 输出：你好，我是张三

In the above example, the `student` object itself does not have a `greet` method, but its prototype` person` has this method, so through the prototype chain, the `student` object can call the `greet` method.

3. Difference:

The difference between prototype and prototype chain lies in their concepts and functions.

- Prototype is an attribute that every object has. It contains some shared attributes and methods and is used to realize the sharing and inheritance of attributes and methods between objects.

- The prototype chain is a mechanism that implements inheritance through the prototype relationship between objects. It defines the inheritance relationship between objects so that objects can share the properties and methods of prototype objects.

The function of the prototype chain is to realize the inheritance relationship between objects. Through the prototype chain, child objects can inherit the properties and methods of the parent object. The role of a prototype is to define the shared properties and methods of an object so that multiple objects can share the properties and methods of the same prototype object.

Summary:

Prototype and prototype chain are important concepts for implementing inheritance in JavaScript. Prototype is an attribute that every object has and is used to define the shared attributes and methods of the object; prototype chain is a mechanism to realize inheritance through the prototype relationship between objects, which defines the inheritance relationship between objects so that the object can Properties and methods of shared prototype objects. Through prototypes and prototype chains, we can realize the sharing and inheritance of properties and methods between objects.

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