javascript - 随机字符始终返回零

Question

在这个片段中，它将随机生成混合单词和数字，但我想知道为什么它总是在第二个字符中返回零？如果您单击刷新按钮，它总是在第二个位置返回 0。有什么想法吗？

$(function() {
  var words = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZ0123456789abcdefghiklmnopqrstuvwxyz"
  var myLength = 4;

  function Captcha() {
    $('#Captcha').html("");
    for (var i = 0; i < myLength; i++) {
      var word = words[Math.floor(Math.random() * words.length)];
      $('#Captcha').append(word + i++);
    }
  }
    Captcha();
 $('#reCaptchaRefresh').click(function(){
  Captcha();
  });
});

#Captcha {
border: 1px solid black;
  padding: 10px;
  float: left;
}

#reCaptchaRefresh {
clear: both;  
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="Captcha" ></div>
<div id="reCaptchaRefresh">
Refresh
</div>

Answer 1

原因是您将 i 附加到输出字符串。您还在每次迭代中将 i 递增两次。试试这个:

$(function() {
  var words = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZ0123456789abcdefghiklmnopqrstuvwxyz"
  var myLength = 4;

  function Captcha() {
    $('#Captcha').empty();

    for (var i = 0; i < myLength; i++) {
      var word = words[Math.floor(Math.random() * words.length)];
      $('#Captcha').append(word); // Note the removal of the concatenation and '++' here
    }
  }

  $('#reCaptchaRefresh').click(Captcha).trigger('click');
});

#Captcha {
  border: 1px solid black;
  padding: 10px;
  float: left;
}
#reCaptchaRefresh {
  clear: both;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="Captcha"></div>
<div id="reCaptchaRefresh">
  Refresh
</div>