• [joint query set & & minimum spanning tree] how many tables, or smooth project


    How many tables Today is Ignatius’ birthday. He invites a lot of friends. Now it’s dinner time. Ignatius wants to know how many tables he needs at least. You have to notice that not all the friends know each other, and all the friends do not want to stay with strangers. One important rule for […]

  • Installing chrome and firebox in Ubuntu


    order This article mainly describes how to install chrome and firebox in docker file. chrome RUN apt-get install -y \ apt-transport-https \ ca-certificates \ curl \ gnupg \ –no-install-recommends RUN curl -sSL https://dl.google.com/linux/linux_signing_key.pub | apt-key add – \ && echo “deb [arch=amd64] https://dl.google.com/linux/chrome/deb/ stable main” > /etc/apt/sources.list.d/google-chrome.list RUN apt-get update ## xdg-icon-resource: No writable system […]

  • Promise, promise, change the function to support both callback and promise


    BeginnersNode.js, withExpressdevelopmentWebProject.And it’s not a small project. It’s very risky. It was relatively simple at the beginning and didn’t use itPromiseIt’s going well,With the deepening of development, it is not necessary toPromiseIt’s too late. So there is a problem that some of the previously written methods are not supportedPromise,If you change it directly toPromiseBefore that, […]

  • Python 3 web crawler Development Practice pdf


    A series of articles: WSL 2 installation is incomplete Python 3 web crawler Development Practice pdf As you can see from the previous articles, I’m learning crawler recently. Although this is useless, it won’t be useful in the future, but I really want to learn it. Then, I consulted some big bulls and consulted a […]

  • Git new get


    Git new get This article is only written for the convenience of reference Delete remote merged local branches 1. View local branches and tracking: git remote show origin You can find branches whose remote branches have been deleted.You can use the following command to delete these branches git remote prune origin Git 2.23 We notice […]

  • No terminal for rstudio in win10?


    Terminal under rstudio is a function launched in 2017, which is quite practical, but the newly installed rstudio may have problems that cannot be found. For example: It’s understandable without bash, but it’s a bit weird without PowerShell.In fact, the problem lies in the setting. Click Tools > Global Options > terminal The default value […]

  • Ubuntu install sublime-text3


    I often use sublime in my work. The current version is a little low and looks ugly, so I simply upgrade it and record the steps: 1. Uninstall the old version sudo apt remove sublime-text 2. Install the new version wget -qO – https://download.sublimetext.com/sublimehq-pub.gpg | sudo apt-key add – echo “deb https://download.sublimetext.com/ apt/stable/” | sudo […]

  • Method to obtain the object object property, Reflect.ownKeys , Object.getOwnPropertyNames , Object.getOwnPropertySymbols , Object.keys ,for in


    let triangle={ a:1, b:2, c:3 }   function coloTriangle(){ this.color=’red’; }   coloTriangle.prototype=triangle; let color=new coloTriangle(); Object.defineProperty(color,’auto’,{ value:’auto’ }) let symbolProp=Symbol(‘symbol’); color[symbolProp]=’symbol’ /** * Reflect.ownKeys:Object.getOwnPropertyNames(target).concat(Object.getOwnPropertySymbols) *None of them come from inheritance. They are all own *It can be traversed regardless of enumeration or not *You can also get the symbol type attribute */ Reflect.ownKeys(color) //[“color”,”auto”,Symbol(symbol)] […]

  • “serve”: ” node_modules/.bin/vue-cli-service serve –open”


    In the Vue cli3 project, start with this configuration “serve”: “node –max_old_space_size=4096 node_modules/.bin/vue-cli-service serve –open”, “build”: “node –max_old_space_size=4096 node_modules/.bin/vue-cli-service build –open”, It is recognized in MAC and Linux, but not in windows? Just change the command or add another line manually to avoid affecting others”dev”: “vue-cli-service serve”Some people get up by NPM run dev,Some people […]

  • The tar command under Linux is decompressed to the specified directory


    Unzip the tar command under Linux to the specified directory: #tar zxvf xx.tar.gz -C /xx//Put the xx.tar.gz Unzip it to / XX / if the directory / XX existsThis is a little different from the CP command. If the CP command does not exist, the directory will be created automatically!  

  • Interviewing a 31 year old IOS developer touched me a little. Where should programmers over 30 go?


    preface Recently HR gave me a resume. I just saw my resume at the age of 31? I’m a little surprised. In fact, development tends to be younger now. Most of them are post-90s and post-95s. After all, software development is not like hardware development. The higher the age, the more popular it is. 31 […]

  • Promise and Reduce


    Promise organization code Promise Ajax version promise, to solve the problem of asynchronous. ajax1().then(ajax2).then(ajax3).then(()=>{}) Comments: it always makes people feel that promise exists for Ajax Some people cleverly encapsulate promise on the pop-up components. //Callback mode Alert (‘are you sure you want to delete this data ‘, () = >{ console.log (‘deleted successfully’) },()=>{ console.log […]