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Explain the implementation of ES5 class and inheritance in detail 1. Preface Class implementation and class inheritance in ES5 is a high point in JS that has to be crossed and conquered. Whether in the process of learning, in order to better understand the implementation method of ES 6 class and learn the knowledge of prototype chain and ...

Lesson 4 Basic _ constraint 1. Summary 1. Concepts Rules that act on fields in a table to restrict data stored in the table. 2. Purpose Ensure that the data is correct, valid and complete. 3. Classification constraintdescribeKeywordNon-empty constraintRestrict the field to data that cannot be nullNOT NULLUnique ConstraintEnsure that all ...

Deep and shallow copyShallow copy: only the reference (address) is copied. That is, after copying, the original variable and the new variable point to the same thing, and their operations will affect each other.Deep copy: reallocate memory in the heap and have different addresses, but the values are the same. The copied object is completely iso ...

Describe the prototype chainbackgroundJavaScript is dynamic and does not provide an implementation of class itself. Even if the class keyword is introduced in ES2015/ES6, it is only a syntax sugar, and JavaScript is still based on the prototypeWhen it comes to inheritance, JavaScript has only one structure: objects. Each instance object has a p ...

Delve into how v-if works <div v-scope="App"></div> <script type="module"> import { createApp } from 'https://unpkg.com/petite-vue?module' createApp({ App: { $template: ` <span v-if="status === 'offline'"> OFFLINE </span> <span v-else-if="status === 'UNKOWN'"> UNKOWN </span> ...

List rendering v-for instruction: 1. Used to display list data 2. Syntax: V-for = "(item, index) in XXX": key = "yyy" 3. Traversable: array, object, string (rarely used), specified number of times (rarely used) [it can also be used for list filtering (fuzzy query) and list sorting sortType (ascending and descending)] How V ...

In CSS specification Scroll-linked Animations In, an epoch-making CSS function is introduced. That is -- The @scroll-timeline At rule, literally translated as rolling timeline.This article will take you to find out, from getting started to learning to use CSS @ scroll timeline.What is @ scroll timeline?What is @ scroll timeline?@Scroll timeline ...

+Use a variable to save one or some elements in the page +There are two types of methods to get elements 1. Get unconventional elements => html: document.documentElement => head: document.head => body: document.body 2. Get general elements 2-1. Get element by id =>Syntax: document Getelementbyid ('element id name ') =>R ...

Learning objectives of this article Be able to understand the concept and function of vue componentsBe able to master the ability of packaging componentsAbility to use communication between componentsAble to complete todo case 1. vue components 1.0_ Why use components I've made a folding panel before Requirements: now you want multiple p ...

1, What is Axios Axios is a promise based HTTP Library (similar to jQuery's Ajax for HTTP requests)Can be used for browsers and node JS (it can be used for both the client and the server written by node.js) 2, What are the features of Axios Support promise APIIntercept requests and responsesConvert request data and response dataCance ...