前端案例:简易登录表单的制作,包括用户名、密码、随机验证码(代码完整

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    user: '', //用户名
    pwd: '', //密码
    code: '', //用户输入的验证码
    rand: [], //随机生成的验证码
    isRem: false,//记住密码
    notRem: true, //不记住密码(默认此选项)
    codeList: ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K',
      'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
      'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'], //随机验证码可选字母
  }
},
methods: {
  //点击登录
  login() {
    //验证码的验证
    var randStr = this.rand.toString().replace(/,/g, ""); //随机生成的验证码为数组形式,此处将其转为字符串并去掉中间相隔的逗号
    var codeStr = this.code; //用户输入的验证码
    if (randStr.toLowerCase() == codeStr.toLowerCase()) { //比较用户输入的与随机生成的验证码,不区分大小写
      this.$message.success('验证码正确,可正常登录')
    } else {
      this.$message.error('请输入正确的验证码');
    }
    //点击登录后的程序逻辑...
  },

  //是否记住密码
  rem() {
    //记住密码
    if (this.notRem == true) {
      this.notRem = false;
      this.isRem = true;
      //...
    } else {
      //不记住密码
      this.notRem = true;
      this.isRem = false;
      //...
    }
  },

  //忘记密码
  forget() {
    console.log("忘记密码");
    //忘记密码后的程序逻辑...
  },

  //绘制验证码
  drawCode() {
    //获取canvas画布
    var canvas = document.getElementById('verifyCanvas');
    var context = canvas.getContext('2d');
    //填充画布
    context.fillStyle = 'cornflowerblue';
    context.fillRect(0, 0, canvas.width, canvas.height);
    //创建渐变
    var gradient = context.createLinearGradient(0, 0, canvas.width, 0);
    gradient.addColorStop('0', 'yellow');
    gradient.addColorStop('0.5', 'black');
    gradient.addColorStop('1.0', 'red');
    //字体
    context.fillStyle = gradient;
    context.font = '30px Arial';
    //验证码的位置
    var x = [];
    var y = [];
    for (let i = 0; i < 4; i++) {
      this.rand[i] = this.codeList[Math.floor(Math.random() * this.codeList.length)];
      x[i] = i * 26 + 10;
      y[i] = 30;
      context.fillText(this.rand[i], x[i], y[i])
    }

    //绘制若干随机点
    for (let i = 0; i < 20; i++) {
      this.drawDot(canvas, context)
    }
    this.convertCanvasToImage(canvas);
    console.log(this.rand);
  },

  drawDot(canvas, context) {
    var px = Math.floor(Math.random() * canvas.width);
    var py = Math.floor(Math.random() * canvas.height);
    context.moveTo(px, py);
    context.lineTo(px + 1, py + 1);
    context.lineWidth = 0.2;
    context.stroke()
  },
  //绘制图片
  convertCanvasToImage(canvas) {
    document.getElementById('verifyCanvas').style.display = 'none';
    var image = document.getElementById('code_img');
    image.src = canvas.toDataURL('image/png');
    return image
  },
  //刷新验证码
  refreshCode() {
    var renew = document.getElementById('codeBox');
    var codeObj = document.getElementById('verifyCanvas');
    renew.removeChild(codeObj);
    var canvas = document.createElement('canvas');
    canvas.width = '112';
    canvas.height = '38';
    canvas.id = 'verifyCanvas';
    renew.appendChild(canvas);
    this.drawCode()
  }
},
mounted() {
  //调用绘制方法
  this.drawCode();
  this.refreshCode()
}

}

.login { background-color: #3a92a4; border: 2px solid black; border-radius: 10px; width: 5.5rem; height: 5.4rem; margin: auto; } .login > p { float: left; color: white; font-family: "Agency FB"; font-size: 25px; font-weight: bolder; margin: 15px 15px; } /*表单区域*/ .form { width: 80%; height: 90%; margin: 1.1rem auto; } .form .userAndPass { margin-bottom: 0.5rem; } /*验证码图片*/ .form #code_img { position: absolute; top: 4.31rem; width: 1.1rem; height: 0.5rem; border: 1px solid #7EDDB4; left: 10.63rem; cursor: pointer; background-color: #E6F9F2; border-radius: 5px; } .userAndPass .txt /deep/ .el-input__inner { border-radius: 5px !important; height: 0.6rem; } /*记住密码*/ .remember { cursor: pointer; width: 50%; display: flex; font-family: SourceHanSansCN-Regular; font-size: 14px; color: #FFFFFF; letter-spacing: 1.29px; font-weight: 400; margin: auto; line-height: 0.2rem; } .remember img { width: 0.2rem; height: 0.2rem; vertical-align: middle; margin-right: 0.05rem; } /*登录按钮*/ .btn { cursor: pointer; width: 65%; height: 0.6rem; text-align: center; position: relative; display: flex; font-family: SourceHanSansCN-Bold; font-size: 20px; color: #FFFFFF; letter-spacing: 2.85px; background-color: #4ec5f0; border-radius: 5px; } .btn p { margin: auto; line-height: 0.6rem; } .btn img { width: 0.15rem; height: 0.15rem; vertical-align: middle; margin-left: 0.4rem; } .forget { cursor: pointer; font-family: SourceHanSansCN-Regular; font-size: 12px; color: #FFFFFF; letter-spacing: 1.12px; text-align: right; margin-top: 0.09rem; } #### css 1,盒模型 2,如何实现一个最大的正方形 3,一行水平居中,多行居左 4,水平垂直居中 5,两栏布局,左边固定,右边自适应,左右不重叠 6,如何实现左右等高布局 7,画三角形 8,link @import导入css 9,BFC理解 ![](https://p6-xtjj-sign.byteimg.com/tos-cn-i-73owjymdk6/bd9f2b64649d4a118ec720f6df7e850c~tplv-73owjymdk6-jj-mark-v1:0:0:0:0:5o6Y6YeR5oqA5pyv56S-5Yy6IEAg55So5oi3NTc5MjMwMTY3MDI=:q75.awebp?rk3s=f64ab15b&x-expires=1771407026&x-signature=cyVrJPEnJ4Z5WEGCz51F5x900HY%3D) #### js 1,判断 js 类型的方式 2,ES5 和 ES6 分别几种方式声明变量 3,闭包的概念?优缺点? 4,浅拷贝和深拷贝 5,数组去重的方法 6,DOM 事件有哪些阶段?谈谈对事件代理的理解 7,js 执行机制、事件循环 8,介绍下 promise.all 9,async 和 await, 10,ES6 的 class 和构造函数的区别 11,transform、translate、transition 分别是什么属性?CSS 中常用的实现动画方式, 12,介绍一下rAF(requestAnimationFrame) 13,javascript 的垃圾回收机制讲一下, 14,对前端性能优化有什么了解?一般都通过那几个方面去优化的? ![](https://p6-xtjj-sign.byteimg.com/tos-cn-i-73owjymdk6/fd19a89872224515a100f70e8ca0cdb9~tplv-73owjymdk6-jj-mark-v1:0:0:0:0:5o6Y6YeR5oqA5pyv56S-5Yy6IEAg55So5oi3NTc5MjMwMTY3MDI=:q75.awebp?rk3s=f64ab15b&x-expires=1771407026&x-signature=FKhBqiaDts8H7H7FMrIiNxlS6g4%3D) **开源分享:https://docs.qq.com/doc/DSmRnRGxvUkxTREhO**