Interesting: dynamic typing effect, background particle effect, four-digit verification code

In the React project, the interesting small plug-ins used such as: dynamic typing effect , background particle effect, draw a four-digit verification code with canvas in css5

 

1. Dynamic typing effect

A js method is encapsulated, which can be used at any time, without further ado, just read the source code directly

test.js file code

expotr const dz=(参数a，参数b)=>{   //使用ES6的箭头函数，a,b参数是前台视图层传过来的
 let str = b,timer=0,i=0;
  funcition typeing(){
     if(i<=str.lenght){
          a.innerHtml = str.slice(0,i++)+'_'
          timer = setTimeout(typeing,200)
      }
      {
     a.innerHtml = str
     clearTimeout(timer)
      }
   }
  return typeing()   //返回typeing
}

View layer code test.jsx

import React, { Component } from 'react'

import {dz} from './../../js/test.js'  //引入test.js文件，使用里面的dz方法


dz=()=>{
  let id = document.getElementById("test")
  let str = "打工人，打工魂"
  dz(id,str)   //使用js里面的方法
}


render
(
  {
   <div id="test"></div>   
   <button onClick={()=>{this.dz()}}>点击</button>
  }
)

2. Background particle effect

First look at the renderings

 

Install directly with npm   npm install --save particles-bg   //不懂什么意思的去百度吧~

 

import Particles  from 'particles-bg'   //引用刚才安装的插件

render
（
  {
     <Particles type="circle" bg={true}/>   //type属性貌似还有lines circle...
  }
）

3. Canvas draws a four-digit verification code in css5

There is a requirement in the project that requires a four-digit verification code. After thinking about it, I made one with canvas

First look at the html code

  <canvas onClick={this.createCode} width="80" height='39' ref={el => this.canvas = el}/>

    //canvas容器

The end is the js code

   // 生成验证码

   createCode = () => {                     //用的是es6中的箭头函数
    const ctx = this.canvas.getContext('2d')
    const chars = [1, 2, 3, 4, 5, 6, 7, 8, 9, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']
    let code = ''
    ctx.clearRect(0, 0, 80, 39)
    for (let i = 0; i < 4; i++) {
      const char = chars[randomNum(0, 57)]
      code += char
      ctx.font = randomNum(20, 25) + 'px SimHei'  //设置字体随机大小，randomNum方法是写了一个取随机数的方法
      ctx.fillStyle = '#D3D7F7'
      ctx.textBaseline = 'middle'
      ctx.shadowOffsetX = randomNum(-3, 3)
      ctx.shadowOffsetY = randomNum(-3, 3)
      ctx.shadowBlur = randomNum(-3, 3)
      ctx.shadowColor = 'rgba(0, 0, 0, 0.3)'
      let x = 80 / 5 * (i + 1)
      let y = 39 / 2
      let deg = randomNum(-25, 25)
      /**设置旋转角度和坐标原点**/
      ctx.translate(x, y)
      ctx.rotate(deg * Math.PI / 180)
      ctx.fillText(char, 0, 0)
      /**恢复旋转角度和坐标原点**/
      ctx.rotate(-deg * Math.PI / 180)
      ctx.translate(-x, -y)
    }

    this.setState({           
      code                //code是变量，我是在react中写，所有用的是setState
    })
  }

Look at the randomNum function method

export function randomNum(min, max) {
              return Math.floor(Math.random() * (max - min) + min);
            }

//min,max是参数，把结果return出去

The renderings are as follows