what is javascript instance

An instance is a concrete product of a class, a real object of a class, and an object is a content structure with multiple attributes; there is no class syntax in JavaScript, so the concept of a class is to create a Object is implemented.

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

Instance is the real object of a class. For example, we are all "human beings", and you and I are both instances of the "human" class. Instantiation is the process of creating an object, created with the New keyword.

What is a javascript instance?

In written language, examples are actual examples.

In computer languages, a "class" is called an "instance" after instantiation. "Classes" are static and do not occupy process memory, while "instances" have dynamic memory. In a database, represents a collection of programs. For example, in Oracle, instances are database programs that can support the operation of the database.

Example:

function start(){
   alert("Bang!!!");
}
  
//constructor
function Car(color, title){
   this.color = color;
   this.title = title;
   this.start = start;
}
 
var obj = {a;1,b:2};
var car1 = new Car("red", "BMW");
var car2 = new Car("yellow", "VOIS");

car1 and car2, both of which are instances. The simple understanding of the example is the finished product. For example, cake. Car is the constructor, which can be understood as a cake mold.

The difference between instances and objects, from a definition point of view:

1. An instance is a concrete product of a class,

2. An object is a product with multiple attributes. Content structure.

Instances are all objects, but not all objects are instances.

There is no syntax for classes (before ES6) in JS, so the concept of a class is realized by creating an object.

Recommended study: "javascript basic tutorial"

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