效果图：

html代码
输入错误三次显示该验证码，isSidentify 为输错次数

<div class="inputYzm vfCode" v-if="isSidentify >= 3">
  <input placeholder="请输入验证码" v-model="sidentifyMode" />
  <div @click="refreshCode()" class="vfCodeComponents" title="点击切换验证码">
    <v-sidentify :identifyCode="identifyCode"></v-sidentify>
  </div>
</div>

定义和方法

data(){
	return {
	  isSidentify: 0,
      sidentifyMode: '',
      identifyCode: '',
      identifyCodes: ['0','1','2','3'...'a','b','c'...'z']//验证码出现的数字和字母
	}
}
methods:{
	//登录
	submit() {
		if (this.isSidentify >= 3) {
	        if (!this.sidentifyMode) {
	          this.$message({
	            type: 'warning',
	            duration: '2000',
	            message: '验证码不能为空！'
	          })
	          return
	        }
	        if (this.sidentifyMode.toLowerCase() != this.identifyCode.toLowerCase()) {
	          this.$message({
	            type: 'warning',
	            duration: '2000',
	            message: '验证码错误！'
	          })
	          this.refreshCode()
	          return
	        }
        }
	},
    // 生成随机数
    randomNum(min, max) {
      max = max + 1
      return Math.floor(Math.random() * (max - min) + min)
    },
    // 更新验证码
    refreshCode() {
      this.identifyCode = ''
      this.makeCode(this.identifyCodes, 4)
      // console.log('当前验证码:', this.identifyCode)
    },
    // 随机生成验证码字符串
    makeCode(data, len) {
      // console.log('data, len:', data, len)
      for (let i = 0; i < len; i++) {
        this.identifyCode += this.identifyCodes[this.randomNum(0, this.identifyCodes.length - 1)]
      }
    },
}

样式

.vfCode {
  background: #fff;
  width: 180px;
  height: 50px;
  border-radius: 25px;
  border: solid 1px #13c2c0;
  margin-top: 38px;
  &.inputYzm {
    background: white url('../img/login-yzm.png') no-repeat 15px center;
    background-size: 35px 35px;
  }
  input {
    background: none;
    border: none;
    outline: none;
    width: 130px;
    height: 100%;
    margin-left: 60px;
    font-size: 16px;
    border-radius: 0px 35px 35px 0px;
    box-shadow: inset 0 0 0 1000px #fff !important;
  }
  .vfCodeComponents {
    position: relative;
    bottom: 43px;
    left: 219px;
    cursor: pointer;
  }
}

验证码组件 identifyCode ,核心代码

<template>
  <div class="s-canvas">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
export default {
  name: 'SIdentify',
  props: {
    identifyCode: {
      type: String,
      default: '1234'
    },
    fontSizeMin: {
      type: Number,
      default: 18
    },
    fontSizeMax: {
      type: Number,
      default: 40
    },
    backgroundColorMin: {
      type: Number,
      default: 180
    },
    backgroundColorMax: {
      type: Number,
      default: 240
    },
    colorMin: {
      type: Number,
      default: 50
    },
    colorMax: {
      type: Number,
      default: 160
    },
    lineColorMin: {
      type: Number,
      default: 40
    },
    lineColorMax: {
      type: Number,
      default: 180
    },
    dotColorMin: {
      type: Number,
      default: 0
    },
    dotColorMax: {
      type: Number,
      default: 255
    },
    contentWidth: {
      type: Number,
      default: 111
    },
    contentHeight: {
      type: Number,
      default: 38
    }
  },
  methods: {
    // 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) {
      let r = this.randomNum(min, max)
      let g = this.randomNum(min, max)
      let b = this.randomNum(min, max)
      return 'rgb(' + r + ',' + g + ',' + b + ')'
    },
    drawPic() {
      let canvas = document.getElementById('s-canvas')
      let 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) // 绘制干扰线
      // this.drawDot(ctx) // 绘制干扰点
    },
    // 绘制文本
    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
      ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
      let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
      let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
      var deg = this.randomNum(-30, 30) // 字符旋转角度(不超过45度比较好)
      // 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)
    },
    drawLine(ctx) {
      // 绘制干扰线
      for (let i = 0; i < 8; 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()
      }
    },
    drawDot(ctx) {
      // 绘制干扰点
      for (let i = 0; i < 100; 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()
      }
    }
  },
  watch: {
    identifyCode() {
      this.drawPic()
    }
  },
  mounted() {
    this.drawPic()
  }
}
</script>

感谢大佬分享，点击 这里