How to implement singleton pattern using ES6
Singleton is a very basic thing in programming. This article mainly introduces you to the relevant information about using ES6 to implement the singleton pattern and its application. The article introduces it in great detail through sample code. Friends who need it can refer to it. For reference, let’s learn with the editor below.
Preface
In the eyes of traditional development engineers, a singleton is to ensure that a class has only one instance. The implementation method is generally to first determine the instance. Whether it exists or not, if it exists, it will be returned directly. If it does not exist, it will be created and returned. This ensures that a class has only one instance object. In JavaScript, a singleton acts as a namespace provider, providing a unique access point to the object from the global namespace.
The definition of singleton mode is to ensure that a class has only one instance and provide a global access point to access it.
The singleton pattern can create objects at the appropriate time and create the only one.
The code is close to life and very interesting. For example, when logging in to a website, a login pop-up box will pop up after clicking login. Even if you click again, the same pop-up box will not appear again. Or in a music player program, if the user opens a piece of music and wants to open another piece of music, the previous playback interface will automatically close and switch to the current playback interface. These are all application scenarios of the singleton pattern.
To implement a singleton pattern, a classic way is to create a class. There is another method in the class that can create an instance object of the class, and there is also a mark to record whether an instance object has been created. If the object already exists, a reference to the first instantiated object is returned.
Implementation of singleton mode
es5 implementation method
var Singleton = function(name) {
this.name = name;
//一个标记，用来判断是否已将创建了该类的实例
this.instance = null;
}
// 提供了一个静态方法，用户可以直接在类上调用
Singleton.getInstance = function(name) {
// 没有实例化的时候创建一个该类的实例
if(!this.instance) {
this.instance = new Singleton(name);
}
// 已经实例化了，返回第一次实例化对象的引用
return this.instance;
}Users can be widely known through a interface to access the instance.
We try to instantiate the object twice and observe whether the two instantiation results point to the same object.
var a = Singleton.getInstance('sven1'); var b = Singleton.getInstance('sven2'); // 指向的是唯一实例化的对象 console.log(a === b);
The return result is: true. Explain that there is a reference relationship between a and b.
es6 implementation
Create the Singleton class. The class keyword and static functions are both new in es6.
class Singleton {
constructor(name) {
this.name = name;
this.instance = null;
}
// 构造一个广为人知的接口，供用户对该类进行实例化
static getInstance(name) {
if(!this.instance) {
this.instance = new Singleton(name);
}
return this.instance;
}
}Application Example of Singleton Mode
We use a common scenario in life to illustrate the application of singleton mode.
On any website, when you click the login button, only one and only one login box will pop up. Even if you click the login button again later, no more pop-up boxes will pop up. This is a typical application of the singleton pattern. Next we implement it. In order to focus on the display of singleton mode, let’s simplify the login box.
The above is the detailed content of How to implement singleton pattern using ES6. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
Is async for es6 or es7?
Jan 29, 2023 pm 05:36 PM
async is es7. async and await are new additions to ES7 and are solutions for asynchronous operations; async/await can be said to be syntactic sugar for co modules and generator functions, solving js asynchronous code with clearer semantics. As the name suggests, async means "asynchronous". Async is used to declare that a function is asynchronous; there is a strict rule between async and await. Both cannot be separated from each other, and await can only be written in async functions.
Common programming paradigms and design patterns in Go language
Mar 04, 2024 pm 06:06 PM
As a modern and efficient programming language, Go language has rich programming paradigms and design patterns that can help developers write high-quality, maintainable code. This article will introduce common programming paradigms and design patterns in the Go language and provide specific code examples. 1. Object-oriented programming In the Go language, you can use structures and methods to implement object-oriented programming. By defining a structure and binding methods to the structure, the object-oriented features of data encapsulation and behavior binding can be achieved. packagemaini
Why does the mini program need to convert es6 to es5?
Nov 21, 2022 pm 06:15 PM
For browser compatibility. As a new specification for JS, ES6 adds a lot of new syntax and API. However, modern browsers do not have high support for the new features of ES6, so ES6 code needs to be converted to ES5 code. In the WeChat web developer tools, babel is used by default to convert the developer's ES6 syntax code into ES5 code that is well supported by all three terminals, helping developers solve development problems caused by different environments; only in the project Just configure and check the "ES6 to ES5" option.
How to implement array deduplication in es5 and es6
Jan 16, 2023 pm 05:09 PM
In es5, you can use the for statement and indexOf() function to achieve array deduplication. The syntax "for(i=0;i<array length;i++){a=newArr.indexOf(arr[i]);if(a== -1){...}}". In es6, you can use the spread operator, Array.from() and Set to remove duplication; you need to first convert the array into a Set object to remove duplication, and then use the spread operator or the Array.from() function to convert the Set object back to an array. Just group.
What does es6 temporary Zenless Zone Zero mean?
Jan 03, 2023 pm 03:56 PM
In es6, the temporary dead zone is a syntax error, which refers to the let and const commands that make the block form a closed scope. Within a code block, before a variable is declared using the let/const command, the variable is unavailable and belongs to the variable's "dead zone" before the variable is declared; this is syntactically called a "temporary dead zone". ES6 stipulates that variable promotion does not occur in temporary dead zones and let and const statements, mainly to reduce runtime errors and prevent the variable from being used before it is declared, resulting in unexpected behavior.
One article to understand the singleton pattern in JavaScript
Apr 25, 2023 pm 07:53 PM
The JS singleton pattern is a commonly used design pattern that ensures that a class has only one instance. This mode is mainly used to manage global variables to avoid naming conflicts and repeated loading. It can also reduce memory usage and improve code maintainability and scalability.
How to determine how many items there are in an array in es6
Jan 18, 2023 pm 07:22 PM
In ES6, you can use the length attribute of the array object to determine how many items there are in the array, that is, to get the number of elements in the array; this attribute can return the number of elements in the array, just use the "array.length" statement. Returns a value representing the number of elements of the array object, that is, the length value.
Will es6 import promote variables?
Jan 18, 2023 pm 07:44 PM
ES6 import will cause variable promotion. Variable hoisting is the promotion of a variable declaration to the very beginning of its scope. js has to go through the compilation and execution phases. During the compilation phase, all variable declarations will be collected and variables declared in advance, and other statements will not change their order. Therefore, during the compilation phase, the first step is already is executed, and the second part is executed only when the statement is executed in the execution phase.
