Array generate array when you need to generate an array of 0-99 scenario 1 const createArr = (n) => Array.from(new Array(n), (v, i) => i) const arr = createArr(100) // 0-99 array scenario 2 const createArr = (n) => new Array(n).fill(0).map((v, i) => i) createArr(100) // 0-99 array disrupt the array when you have an array, you need to disrupt the sorting of the array const randomSort = list => list.sort(() => Math.random() - 0.5) randomSort([0,1,2,3,4,5,6,7,8,9]) // randomly arrange the results Array deduplication when you need to keep only one for all the repeating elements in the array const removeDuplicates = list => [...new Set(list)] removeDuplicates([0, 0, 2, 4, 5]) // [0,2,4,5] most groups take intersection when you need to take the intersection of multiple arrays const intersection = (a, ...arr) => [...new Set(a)].filter((v) => arr.every((b) => b.includes(v))) intersection([1, 2, 3, 4], [2, 3, 4, 7, 8], [1, 3, 4, 9]) // [3, 4] find maximum index but you need to find an index of the largest value in the array const indexOfMax = (arr) => arr.reduce((prev, curr, i, a) => (curr > a[prev] ? i : prev), 0); indexOfMax([1, 3, 9, 7, 5]); // 2 find the minimum index when you need to find the index of the lowest value in an array const indexOfMin = (arr) => arr.reduce((prev, curr, i, a) => (curr < a[prev] ? i : prev), 0) indexOfMin([2, 5, 3, 4, 1, 0, 9]) // 5 find the nearest value when you need to find the closest value in an array const closest = (arr,…

React Router is a routing library for React applications that provides an easy way to match URL to components. React Router implements the following main concepts: Router: it provides the basic routing capabilities of the application. Routes: it defines the mapping between URL and components. Link: it provides a convenient way to navigate through the application. Switch: it is used to ensure that only one route can match the current URL. createBrowserHistory: this is used to create an instance of HTML5 History API. next, we will delve into the implementation principle of React Router. We will first discuss the implementation of Router components, then discuss the implementation of Routes components, and finally discuss the implementation of Link components. implementation of Router components The Router component is the core component of the React Router library, which provides the basic routing capabilities of the application. The following is the simplified version of the Router component implementation code: const Router = ({ children }) => { const [location, setLocation] = useState(window.location.pathname); useEffect(() => { const handlePopState = () => setLocation(window.location.pathname); window.addEventListener('popstate', handlePopState); return () => window.removeEventListener('popstate', handlePopState); }, []); return <RouterContext.Provider value={{ location }}>{children}</RouterContext.Provider>; }; in the above code, we first define a Router component. It accepts a children attribute, which is the root component of our application. Then we use useState Hook to create a state variable named location . It will be used to track the current URL. We will update this state variable using the setLocation function. next, we use useEffect Hook to register a function that listens for popstate…

Preface Dropdown drop-down menu import import Dropdown from '@/components/Dropdown/Dropdown' The use of subcomponents is as follows: const MenuItem = Dropdown.MenuItem; const SubMenu = Dropdown.SubMenu; Props 1. trigger Type: string (required) default: click | hover description: drop-down trigger mode, click click trigger menu, hover trigger menu 2. onClickMenu Type: func default value: no description: click to trigger the callback function to change the classname of the sub-component. Input parameters: {string} trigger drop-down trigger mode 3. title Type: string default value: no description: drop-down button prompts for title MenuItem child content components import import Dropdown from '@/components/Dropdown/Dropdown'; Props 1. trigger Type: string (required) default: click | hover description: drop-down trigger mode, click click trigger menu, hover trigger menu 2. className Type: string (required) default: click | hover description: class:'dropdownType-click' of the outer div of the sub-content | 'dropdownType-hover' 3. disabled Type: bool default value: false Note: the sub-content of the drop-down is grayed out, true is grayed out, false is normal 4. onClickMenuItem Type: func (required) default value: no description: click on a single sub-content to perform the action. Input parameters: {string | number} value | some item selected by key parent of SubMenu child content import import Dropdown from '@/components/Dropdown/Dropdown'; Props 1. trigger Type: string (required) default: click | hover description: drop-down trigger mode, click click trigger menu, hover trigger menu 2. className Type: string (required) default: click | hover description: class:'dropdownType-click' of the outer div of the sub-content | 'dropdownType-hover' 4. title Type: string default value: no description: drop-down button prompts for title Let's implement dropdown.js import React from 'react';…

on March 17, one year after the launch of the Beta version of the new React document, React finally officially released the new React official document! The new document enables a new domain name: react.dev/ . However, at present, the new document has only been released in English at present When accessing Beta documents ( beta.reactjs.org/ ) and English documents ( reactjs.org/ ) Will be redirected to the new domain name ( react.dev/ ). The new document does not currently provide access to documents in other languages. to access the old Chinese version of the document, you can visit zh-hans.reactjs.org/ . to access the old English version, you can visit legacy.reactjs.org/ . the new document mainly contains the following sections: tutorials and guides : a large number of tutorials and guides are available to help developers learn React from scratch or delve into specific topics. Code samples and demos : provides a series of code examples and demos that demonstrate the power and flexibility of React. Best practices and techniques : learn the latest React best practices and techniques and learn how to optimize your code for better performance. Community Forum : contact other React developers to get help on the project or share expertise in the community. News and updates : get the latest versions, updates, and news from the React development team for the first time. Let's take a look at the features of the new React document! full hug Hooks when Hooks was released in 2018, the Hooks document assumed that the reader was already familiar with…