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用canvas画布实现验证码

作者:互联网

一、代码

<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* #vas {
      border: 1px solid red;
    } */
  </style>
</head>

<body>
  <!-- 修改画布的大小一般使用行内是修改,css修改的像素的排布 -->
  <canvas id="vas" width="160" height="50">浏览器不支持输出的文字</canvas>
</body>
<script>
  let vas = document.querySelector('#vas')
  verify(vas)
  vas.addEventListener('click', () => {
    verify(vas)
  })
  function verify(vas) {
    let code = randStr(5)
    let ctx = vas.getContext('2d')
    ctx.fillStyle = 'blue'
    ctx.fillRect(0, 0, 160, 50)
    ctx.font = '700 20px 黑体'
    ctx.fillStyle = 'red'
    ctx.fillText(code, 30, 30)
  }

  // 返回自定数量的随机字符串
  function randStr(count) {
    let str = '1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
    let code = ''
    for (let i = 0; i < count; i++) {
      let index = rand(0, str.length - 1)
      code += str.charAt(index) + ' '
    }
    //返回随机数字
    function rand(min, max) {
      return Math.floor(Math.random() * (max - min + 1)) + min
    }
    return code
  }
</script>

</html>

实现:生成5个随机数用来实现验证码功能

标签:canvas,code,min,verify,ctx,验证码,画布,let,vas
来源: https://blog.csdn.net/a2739294436/article/details/121459406