What is the javascript prototype method?

javascript prototype refers to the prototype object of javascript, and all JavaScript objects inherit properties and methods from a prototype, which is the prototype object.

The operating environment of this article: windows7 system, javascript version 1.8.5, Dell G3 computer.

What is the javascript prototype method?

JavaScript prototype (prototype object)

All JavaScript objects inherit properties and methods from a prototype (prototype object).

prototype inheritance

All JavaScript objects inherit properties and methods from a prototype (prototype object):

Date 对象从 Date.prototype 继承。
Array 对象从 Array.prototype 继承。
Person 对象从 Person.prototype 继承。

All objects in JavaScript They are all instances of Object at the top of the prototype chain.

JavaScript objects have a chain pointing to a prototype object. When trying to access a property of an object, it not only searches on the object, but also searches on the prototype of the object, and the prototype of the prototype of the object, and searches upwards until it finds a property with a matching name or reaches the prototype. end of chain.

Date objects, Array objects, and Person objects inherit from Object.prototype.

Add properties and methods

Sometimes we want to add new properties or methods to all existing objects.

In addition, sometimes we want to add properties or methods to the object's constructor.

Using the prototype attribute, you can add new attributes to the object's constructor:

Instance

function Person(first, last, age, eyecolor) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eyecolor;
}
 
Person.prototype.nationality = "English";

Of course, we can also use the prototype attribute. Add a new method to the object's constructor:

Instance

function Person(first, last, age, eyecolor) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eyecolor;
}
 
Person.prototype.name = function() {
  return this.firstName + " " + this.lastName;
};

Recommended study: "javascript basic tutorial"

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