首先看一下效果，点击可随机改变验证码

创建一个组件,verificationCode.vue

<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: 35
    },
    fontSizeMax: {
      type: Number,
      default: 35
    },
    backgroundColorMin: {
      type: Number,
      default: 180
    },
    backgroundColorMax: {
      type: Number,
      default: 240
    },
    colorMin: {
      type: Number,
      default: 50
    },
    colorMax: {
      type: Number,
      default: 160
    },
    lineColorMin: {
      type: Number,
      default: 100
    },
    lineColorMax: {
      type: Number,
      default: 200
    },
    dotColorMin: {
      type: Number,
      default: 0
    },
    dotColorMax: {
      type: Number,
      default: 255
    },
    contentWidth: {
      type: Number,
      default: 120
    },
    contentHeight: {
      type: Number,
      default: 40
    }
  },
  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 + ")";
    },
    transparent() {
      return "rgb(255,255,255)";
    },
    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.fillStyle = this.transparent();
      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);
      }
   //绘制背景
       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";
      let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
      let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
      var deg = this.randomNum(-10, 10);
      // 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>

如何使用呢??

<template>
  <div class="get-code" @click="refreshCode()">
    <s-identify :identifyCode="identifyCode"></s-identify>
  </div>
</template>

<script>
import SIdentify from "./components/SIdentify";
export default {
  components: {
    SIdentify,
  },
  data() {
    return {
      identifyCode: "",
      identifyCodes: "0123456789abcdwerwshdjeJKDHRJHKOOPLMKQ", //绘制的随机数
    };
  },
  created() {
    this.refreshCode();
  },
  methods: {
    refreshCode() {
      this.identifyCode = "";
      this.makeCode(this.identifyCodes, 4);
    },
    randomNum(min, max) {
      max = max + 1;
      return Math.floor(Math.random() * (max - min) + min);
    },
    // 随机生成验证码字符串
    makeCode(data, len) {
      for (let i = 0; i < len; i++) {
        this.identifyCode += data[this.randomNum(0, data.length - 1)];
      }
    },
  },
};
</script>

<style>
</style>

完事