Programmer Group

1, Algorithm ++n n + + differences int n=1,n1,n2; n1=++n; System.out.println(n1); System.out.println(n); n2=n++; System.out.println(n2); System.out.println(n); 2 2 2 3 1. Concept Philosophy of writing algorithms: From simple to complex: verify step by step and print more intermediate results Part first and then whole: subdivide when ...

Deep component Provide/Inject Usually, we use prop when we need to transfer data from the parent component to the child component. However, for deeply nested component systems, sometimes deep sub components need part of the contents of the parent component. At this time, it will be very troublesome to still use the prop mechanism. For examp ...

HTML direction Call system functions Use < a > to quickly call the mobile device's three communication functions of phone / SMS / email, and use < input > to quickly call the mobile device's Library / file. These functions facilitate the interaction between the page and the system. The key is that the call format must be accurate ...

1, What problems have been solved? Hook is a special function starting with use (useState, useEffect, etc.), which can only be used inside the function component. It allows you to use state and other React features without writing class. For example, useState is equivalent to the state object in the class component. 1. Update instructions for ...

1. What is a bag? The third-party module in Node.js is also called a package. It is developed by a third-party individual or team and is free for everyone to use 2. Package classification Project package – development dependency package (stored in devdependences directory) – production dependency package (stored in the depend ...

2021.9.1 Pit 57 (component folding): simple folding to the left without animation. The effect is to click the long bar with arrow (added background color for easy viewing) to change the folding state. The idea is that the outer package flex is automatically arranged from left to right, use v-show to control the display of inner elements, and u ...

I. Build projects and install plug-ins # Install vue-cli npm install vue-cli -g # Initialize project vue init webpack china-map # Cut into Catalog cd china-map # Installation Project Dependency npm install # Install vuex npm install vuex --save # Install axios npm install axios --save # Install ECharts npm install echarts --save II. Pr ...

express Learning (3) - cookie s and session s Cookies exist in the browser and can only store up to 4K of data, which is not safe Session exists in the server and cannot be independent (read cookie s before session), which is more secure cookie tool Send cookie s: Write the basics first: const express = require('express'); var server=expre ...

1. Install firstNode.jsEnvironment Official Website Address https://nodejs.org/en/ Text editor chooses sublime text3 (vs is too big) 2. Establishing projects 2.1 Create a new project folder, code-x code number x plan, and put it on the desktop 2.2 Initialization cd c:\user\duab\desktop\code-x npm install -g vue-cli //Global Installation vue-c ...

1. Install firstNode.jsEnvironment Official Website Address https://nodejs.org/en/ Text editor chooses sublime text3 (vs is too big) 2. Establishing projects 2.1 Create a new project folder, code-x code number x plan, and put it on the desktop 2.2 Initialization cd c:\user\duab\desktop\code-x npm install -g vue-cli //Global Installation vue-c ...