cnpm i svg-captcha --save

var svgCaptcha = require('svg-captcha');

const cookieParase = require('cookie-parser');
app.use(cookieParase());

// 獲取驗證碼
 getCaptcha(req, res, next){
 var captcha = svgCaptcha.create({ 
 // 翻轉顏色 
 inverse: false, 
 // 字體大小 
 fontSize: 36, 
 // 噪聲線條數 
 noise: 2, 
 // 寬度 
 width: 80, 
 // 高度 
 height: 30, 
 }); 
 // 保存到session,忽略大小寫 
 req.session = captcha.text.toLowerCase(); 
 console.log(req.session); //0xtg 生成的驗證碼
 //保存到cookie 方便前端調用驗證
 res.cookie('captcha', req.session); 
 res.setHeader('Content-Type', 'image/svg+xml');
 res.write(String(captcha.data));
 res.end();
 },

// 獲取驗證碼
router.get('/api/getCaptcha', function(req, res, next) {
 return api.getCaptcha(req, res, next);
})

<img src="/api/getCaptcha" alt="captcha" >

<a href="#" rel="external nofollow" @click="editCaptcha">
 <img src="/api/getCaptcha" alt="" ref="imgYzm">
</a>

editCaptcha () {
 this.$refs.imgYzm.src = '/api/getCaptcha?d='+Math.random()
},

let captcha = document.cookie.split('=')[1]
 if(this.yzm != captcha){
 return this.$message.warning('驗證碼錯誤')
 }