小编给大家分享一下js中什么是类，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
什么是类？
类(class)是在 JS 中编写构造函数的新方法。它是使用构造函数的语法糖，在底层中使用仍然是原型和基于原型的继承。
//ES5 Version
function Person(firstName, lastName, age, address){
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
this.address = address;
}
Person.self = function(){
return this;
}
Person.prototype.toString = function(){
return "[object Person]";
}
Person.prototype.getFullName = function (){
return this.firstName + " " + this.lastName;
}
//ES6 Version
class Person {
constructor(firstName, lastName, age, address){
this.lastName = lastName;
this.firstName = firstName;
this.age = age;
this.address = address;
}
static self() {
return this;
}
toString(){
return "[object Person]";
}
getFullName(){
return `${this.firstName} ${this.lastName}`;
}
}重写方法并从另一个类继承。
//ES5 VersionEmployee.prototype = Object.create(Person.prototype);function Employee(firstName, lastName, age, address, jobTitle, yearStarted) {
Person.call(this, firstName, lastName, age, address);
this.jobTitle = jobTitle;
this.yearStarted = yearStarted;}Employee.prototype.describe = function () {
return `I am ${this.getFullName()} and I have a position of ${this.jobTitle} and I started at ${this.yearStarted}`;}Employee.prototype.toString = function () {
return "[object Employee]";}//ES6 Versionclass Employee extends Person { //Inherits from "Person" class
constructor(firstName, lastName, age, address, jobTitle, yearStarted) {
super(firstName, lastName, age, address);
this.jobTitle = jobTitle;
this.yearStarted = yearStarted;
}
describe() {
return `I am ${this.getFullName()} and I have a position of ${this.jobTitle} and I started at ${this.yearStarted}`;
}
toString() { // Overriding the "toString" method of "Person"
return "[object Employee]";
}}所以我们要怎么知道它在内部使用原型？
class Something {}function AnotherSomething(){}const as = new AnotherSomething();
const s = new Something();
console.log(typeof Something);
// "function"console.log(typeof AnotherSomething);
// "function"console.log(as.toString());
// "[object Object]"console.log(as.toString());
// "[object Object]"console.log(as.toString === Object.prototype.toString);
// trueconsole.log(s.toString === Object.prototype.toString); // true以上是“js中什么是类”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注编程网行业资讯频道！
