vue验证码随机-支持字母和数字随机

canvas绘制干扰点干扰线，可根据需求自行修改

// canvas 绘制干扰点干扰线
<template>
  <div :class="className" @click="createdCode">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
import Vue from 'vue'
export default Vue.extend({
  props: {
    //  配合drawPic限制更新对应canvas，防止以下更新所有的了（不需要阻止可去除）
    className:{
      type:String,
      default:'s-canvas'
    },
    fontSizeMin: {
      type: Number,
      default: 25
    },
    fontSizeMax: {
      type: Number,
      default: 30
    },
    backgroundColorMin: {
      type: Number,
      default: 255
    },
    backgroundColorMax: {
      type: Number,
      default: 255
    },
    colorMin: {
      type: Number,
      default: 0
    },
    colorMax: {
      type: Number,
      default: 160
    },
    lineColorMin: {
      type: Number,
      default: 100
    },
    lineColorMax: {
      type: Number,
      default: 255
    },
    dotColorMin: {
      type: Number,
      default: 0
    },
    dotColorMax: {
      type: Number,
      default: 255
    },
    contentWidth: {
      type: Number,
      default: 120
    },
    contentHeight: {
      type: Number,
      default: 34
    }
  },
  data () {
    return {
      identifyCode: ''
    }
  },
  mounted () {
    this.createdCode()
  },
  methods: {
    // 生成4个随机数
    createdCode () {
      const len = 4
      const codeList = []
      const chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz0123456789'
      const charsLen = chars.length
      for (let i = 0; i < len; i++) {
        codeList.push(chars.charAt(Math.floor(Math.random() * charsLen)))
      }
      this.identifyCode = codeList.join('')
    //  可自行大小写或更多验证
      this.$emit('getIdentifyCode', this.identifyCode.toLowerCase())
      this.drawPic()
    },

    // 生成一个随机数
    randomNum (min, max) {
      return Math.floor(Math.random() * (max - min) + min)
    },
    // 生成一个随机的颜色
    randomColor (min, max) {
      const r = this.randomNum(min, max)
      const g = this.randomNum(min, max)
      const b = this.randomNum(min, max)
      return 'rgb(' + r + ',' + g + ',' + b + ')'
    },

    drawPic () {
      const canvas = document.querySelectorAll(`.${this.className} canvas`);
      const ctx = canvas.getContext('2d')
      ctx.textBaseline = 'bottom'
      // 绘制背景
      ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
      ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
      // 绘制文字
      for (let i = 0; i < this.identifyCode.length; i++) {
        this.drawText(ctx, this.identifyCode[i], i)
      }
      this.drawLine(ctx)
      this.drawDot(ctx)
    },

    drawText (ctx, txt, i) {
      ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
      ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
      const x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
      const y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
      var deg = this.randomNum(-45, 45)
      // 修改坐标原点和旋转角度
      ctx.translate(x, y)
      ctx.rotate(deg * Math.PI / 180)
      ctx.fillText(txt, 0, 0)
      // 恢复坐标原点和旋转角度
      ctx.rotate(-deg * Math.PI / 180)
      ctx.translate(-x, -y)
    },

    // 绘制干扰线
    drawLine (ctx) {
      for (let i = 0; i < 5; i++) {
        ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
        ctx.beginPath()
        ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
        ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
        ctx.stroke()
      }
    },

    // 绘制干扰点
    drawDot (ctx) {
      for (let i = 0; i < 80; i++) {
        ctx.fillStyle = this.randomColor(0, 255)
        ctx.beginPath()
        ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
        ctx.fill()
      }
    }
  }
})
</script>
<style scoped>
.s-canvas {
  height: 38px;
  cursor: pointer;
}
.s-canvas canvas{
  margin-top: 1px;
  margin-left: 8px;
}
</style>