• Go language 2019 survey report released (including download of go Language Atlas)


    < official account, reply to Go, you can download clear knowledge map > For those who are interested in go but don’t know where to start, they can refer to the go language series: Why do you choose go? Go failure oriented programming Enter 2020 with server programming Diamond Sutra Can I ask where is […]

  • Chapter 4 bjrobot linear speed correction


    BJROBOT Linear velocity correction   1.The carLay flatOn the floor, use a tape measure as the measuring scale,Select the front or rear of the car as the starting point of the car, Open the virtual machine in the data and open a terminal ssh In the past, the main control terminal started roslaunch znjrobot bringup.launch。 2.Open […]

  • Scale of SVG after zooming in and out


    function getCoords(evt) { / / calculate the ratio of the current screen to SVG    var canvas = document.getElementById(“canvase”);    var viewbox = svgRoot.getAttributeNS (null, “viewbox”); / / get the viewbox property    var params = viewbox.split(” “);/ / the ratio of screen to SVG. This is the initialization ratio    var roteX =  svgRoot.clientWidth / parseFloat(params[2])  ;    var […]

  • Vue cutter image


    1、 How to install cnpm i vue-cropper –save Intra component call import { VueCropper } from ‘vue-cropper’ components: { VueCropper } 2、 Examples of use <template> <div class=”cropper-wrapper”> <div class=”info-groups”> <label class=”btn btn-orange” for=”uploads” style=” display:inline-block;width : 70px; padding: 0; text align: Center; line height: 28px; “> select Picture < / label >” <input type=”file” […]

  • On the layout of REM mobile terminal


    Using REM to realize adaptive layout should be a major trend of mobile front-end. Some people are still confused about this. They don’t understand how REM realizes adaptive layout and how to adjust the value of REM according to the design draft? How to use sprite background for REM layout? REM do you have to […]

  • Develop tecdat: see how twitter data “shape” regional image


    “ In today’s highly informationized society, social media provides us with a window to know the outside world directly, which determines everyone’s cognition of a region, like a pair of “invisible” hands to shape the image of a region. ▼ According to this background, tecdat analyzes the hot tweets in Ningxia, which are known as […]

  • Svg scale after zooming in and out


    function getCoords(evt) { / / calculate the ratio of the current screen to svg    var canvas = document.getElementById(“canvase”);Var viewbox = svgroot.getattributens (null, “viewbox”); / / get the viewbox attribute    var params = viewbox.split(” “);/ / ratio of screen to SVG this is the initialization ratio    var roteX =  svgRoot.clientWidth / parseFloat(params[2])  ;    var roteY =  […]

  • Intersectionobserver scrolling


    IntersectionObserver Definition It is to listen for the root element and the target element to trigger a callback at the specified cross proportion Compatibility Compatible with part of the modern browser (chrome) production environment, please pay attention to the compatibility requirements Usage scenarios Onscroll can be replaced in certain scenarios1. More simple and elegant writing2. […]

  • Technology sharing | delete statement causes a lot of SQL to be killed


    Author: Wang HangweiYou like MySQL DBA, good at analyzing and solving database performance problems, and using automation tools to solve daily needs. phenomenon A database often sends out the following alarms at a certain time, such as 2:00 a.m. or some time in the daytime [critical] [prod] [MySQL] – over 200 kill SQL / min […]

  • How to control the proportion of flex subelements on the spindle


    background Flex layout is more effective to achieve alignment and space allocation. Recently, I learned the size calculation rules of flex sub elements, mainlyflex-grow, flex-shrinkThe learning of calculation rules. I. Basic Concepts 1.1 main axis The beginning and direction of the layout of flex elements are defined, and the flex sub elements are placed on […]