• Detailed explanation of Middleware in Redux learning


    What is middleware Middleware, translated as middleware, is a very abstract noun. According to my understanding, “middle” is an adjective, and “piece” should be a noun. So let’s focus on itmiddleThis word, middle, is on the top, middle? In fact, it isInsert some other code in the middle of your normal business code, specificIt can […]

  • Map () method


    effect: The map () method returns a new array. The elements in the array are the values of the original array elements after calling the function Grammar: array.map(function(currentValue,index,arr), thisValue) Currentvalue, required, the value of the current element Index, optional, the index value of the current element in the array Arr optional, the array object to […]

  • [jQuery] judge the expansion of multiple lines according to the height


    Multiline expansion Introduction more box is a div that determines whether to add an expansion arrow based on the height This is the icon of Ali font library (can be ignored) <!DOCTYPE html> <html lang=”en”> <head> <meta charset=”UTF-8″> <title>Document</title> <style> .cor-introduce{ line-height: 24px; color: #999; position: relative; overflow: hidden; } .introduce-more-box{ text-align: right; } .intro-more{ […]

  • A simple Sketchpad


    design sketch Project address:https://github.com/lll1024/JV… explain This is a simple Sketchpad that can draw Double arrows, single arrows, graffiti, etc., and can also be edited and undone. There are two classes in total: JVDrawingLayer: inherited fromCAShapeLayerBased on the passed in enumeration value type, different shapes are drawn based on the Bezier curve. JVDrawingView: responsible for display […]

  • How does scratch record the trajectory of arrow rotation?


    In scratch 2.0, we can use the stamp tool to record the trajectory of the character’s movement. How to achieve this? Let’s take a look at the detailed tutorial. Software name: Scratch 2 (graphical programming tool) v2.0 official free green version Software size: 42.1MB Update time: 2016-01-15Download now 1. Open scratch 2.0 and enter its […]

  • Common problems of this direction in JS


    Whether in the job or interview, this points to the problem is often encountered. So this article lists the common points to the problem for everyone, avoid stepping on the pit. First of all, we need to know,In a function, the value of this is determined when the function is called and executed, but not […]

  • Add an edit picture component to your Vue project


    Recommend a powerful image editing plug-intui.image-editor Quick experience Preferred to install in your front-end project: npm i tui-image-editor // or yarn add tui-image-editor Now you’re going to build one.vueFile, copy in the following code: <template> <div id=”tui-image-editor”></div> </template> <script> import “tui-image-editor/dist/tui-image-editor.css”; import “tui-color-picker/dist/tui-color-picker.css”; const ImageEditor = require(“tui-image-editor”); export default { data() { return { instance: […]

  • Method of transforming flat data into tree data in JS front end


    1. JS front-end method to convert flat data into tree data The measurement is successful https://segmentfault.com/a/1190000022444269 //Convert peer data into tree structure listToTree(dataSource) { //Datasource is the same level data source return dataSource.filter(e => { const pid = e.parentId const resultArr = dataSource.filter(ele => { if (ele.menuId === pid) { if (!ele.children) { ele.children = […]

  • ES6 = > arrow function


    Use the arrow function to define the function: var f=v=>v; //Equivalent to var f=function(v){ return v; }; If the arrow function does not require parameters: var f=()=>5; //Equivalent to var f=function(){return 5}; If the arrow function has more than one parameter: var sum = (num1,num2)=>num1+num2; //Equivalent to var sum = function(num1,num2){ return num1+num2; }; If […]

  • The analysis of this direction in ordinary function and arrow function


    Content This of ordinary functions This of arrow function Ordinary function 1. Conclusion Let’s start with the conclusion,The direction of this of an ordinary function cannot be determined when the function is defined. Only when the function is executed can we determine who this is pointing to. In fact, this ultimately points to the object […]

  • CSS3 write white triangle arrow with border


    By the way, I’ve been looking for this kind of hollow arrow before I finally want to share it with you~ The first method uses the common after pseudo element <!DOCTYPE html> <html> <head> <meta charset=”UTF-8″> <title></title> <style type=”text/css”> .arrow { width: 20px; height: 4px; margin: 0 auto 7px; border-left: 4px solid transparent; border-right: 4px […]

  • How to get started with writing


    This paper mainly introduces how to start quicklyMermaidFlow chart, no map upload, no drag and drop drawing, real-time rendering flow chart based on source code, easy to operate and widely integrated into mainstream editors, includingmarkdownWriting environment Through this section, you will learn the following main contents: Understand what a flowchart is andMermaidflow chart; Master and […]