3 implementation methods: 1. Set data structure and "Array.from()" deduplication, syntax "Array.from(new Set(arr))"; 2. Set data structure and extension operator "..." to remove duplicates, the syntax is "[...new Set(arr)]"; 3. filter() and indexOf() filtering, the syntax is "arr.filter((it,in)=>{return arr .indexOf(it,0)===in;});".
The operating environment of this tutorial: Windows 7 system, ECMAScript version 6, Dell G3 computer.
5 ways to remove duplicates from ES6 arrays
1. Set data structure and Array.from() Repeat
#Set is a new data structure provided by ES6, which is similar to an array, but has no duplicate values. Using this feature, we can convert the array to a Set type for deduplication, and then use the Array.from method to convert it to an array again.
The Array.from method is used to convert two types of objects into real arrays: array-like objects and iterable objects (including ES6 new Additional data structures Set and Map).
Implementation idea:
-
After converting the array into a set collection to remove duplication, use the Array.from method to convert the set into an array
Syntax:
Array.from(new Set(arr))
Example:
let arr=[1,2,3,3,2,"1",0,undefined,undefined]; let newArr=Array.from(new Set(arr)); console.log(newArr);
2. Set data structure and extended operations The operator "..." is used to remove duplicates
The expansion operator
…
is introduced in ES6 and expands the iterable object into its separate elements. , the so-called iterable object is any object that can be traversed using a for of loop, such as: array, string, Map, Set, DOM node, etc.
Implementation idea:
After converting the array into a set collection to remove duplication, use the spread operator... to expand the set into an array, and Convert a collection to an array
Syntax:
[...new Set(arr)]
Example:
let arr=[1,2,3,3,2,"1",0,1,2]; let newArr=[...new Set(arr)]; console.log(newArr);
3. Use arrays The filter indexOf method removes duplicates
The filter() method creates a new array, and the elements in the new array are checked by checking all elements in the specified array that meet the conditions.
The indexOf method returns the first index (index) of the specified element in the array, if not, returns -1
Example:
var arr=[1, 2, 3, 2, 3]; var newArr = arr.filter((item,index)=> { return arr.indexOf(item,0) === index; }); console.log(newArr);
So the index values returned by each element in the arr array here through the indexOf() method are 0 1 2 1 2
arr.forEach(item => console.log(arr.indexOf(item))); // 0 1 2 1 2
You can use indexOf to achieve deduplication, such as in arr The fourth element 2 returns an index of 1 through indexOf, but its current index subscript is 3, which is not equal, indicating that the current 2 element has appeared before, so it should be filtered out.
【Related recommendations: javascript video tutorial, web front-end】
The above is the detailed content of How to implement arr (array) deduplication in es6. For more information, please follow other related articles on the PHP Chinese website!

To integrate React into HTML, follow these steps: 1. Introduce React and ReactDOM in HTML files. 2. Define a React component. 3. Render the component into HTML elements using ReactDOM. Through these steps, static HTML pages can be transformed into dynamic, interactive experiences.

React’s popularity includes its performance optimization, component reuse and a rich ecosystem. 1. Performance optimization achieves efficient updates through virtual DOM and diffing mechanisms. 2. Component Reuse Reduces duplicate code by reusable components. 3. Rich ecosystem and one-way data flow enhance the development experience.

React is the tool of choice for building dynamic and interactive user interfaces. 1) Componentization and JSX make UI splitting and reusing simple. 2) State management is implemented through the useState hook to trigger UI updates. 3) The event processing mechanism responds to user interaction and improves user experience.

React is a front-end framework for building user interfaces; a back-end framework is used to build server-side applications. React provides componentized and efficient UI updates, and the backend framework provides a complete backend service solution. When choosing a technology stack, project requirements, team skills, and scalability should be considered.

The relationship between HTML and React is the core of front-end development, and they jointly build the user interface of modern web applications. 1) HTML defines the content structure and semantics, and React builds a dynamic interface through componentization. 2) React components use JSX syntax to embed HTML to achieve intelligent rendering. 3) Component life cycle manages HTML rendering and updates dynamically according to state and attributes. 4) Use components to optimize HTML structure and improve maintainability. 5) Performance optimization includes avoiding unnecessary rendering, using key attributes, and keeping the component single responsibility.

React is the preferred tool for building interactive front-end experiences. 1) React simplifies UI development through componentization and virtual DOM. 2) Components are divided into function components and class components. Function components are simpler and class components provide more life cycle methods. 3) The working principle of React relies on virtual DOM and reconciliation algorithm to improve performance. 4) State management uses useState or this.state, and life cycle methods such as componentDidMount are used for specific logic. 5) Basic usage includes creating components and managing state, and advanced usage involves custom hooks and performance optimization. 6) Common errors include improper status updates and performance issues, debugging skills include using ReactDevTools and Excellent

React is a JavaScript library for building user interfaces, with its core components and state management. 1) Simplify UI development through componentization and state management. 2) The working principle includes reconciliation and rendering, and optimization can be implemented through React.memo and useMemo. 3) The basic usage is to create and render components, and the advanced usage includes using Hooks and ContextAPI. 4) Common errors such as improper status update, you can use ReactDevTools to debug. 5) Performance optimization includes using React.memo, virtualization lists and CodeSplitting, and keeping code readable and maintainable is best practice.

React combines JSX and HTML to improve user experience. 1) JSX embeds HTML to make development more intuitive. 2) The virtual DOM mechanism optimizes performance and reduces DOM operations. 3) Component-based management UI to improve maintainability. 4) State management and event processing enhance interactivity.


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

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Dreamweaver Mac version
Visual web development tools

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

SublimeText3 English version
Recommended: Win version, supports code prompts!