javascript - 如何使用单个按钮单击来更改占位符并在同一按钮单击事件上捕获新数据

Question

<div id="abc" class="first">
           <input type="text" placeholder="Number" id="no" class="contact">
           <input type="text" placeholder="Pass"  id="pass" class="password">
 <div class="btn1" role="group">
         <button type="button" onclick="change()" class="btnregi">Register 
        </button>
  </div>  

    ----------
    javascript function
    var entry=0;
    function change()
        {

         if(entry==0)
      {
       document.getElementById("no").placeholder = "Enter user name...";
       document.getElementById("pass").placeholder = "Enter user password";
       entry++;
      }
       else 
       {
          var newuser=document.getelementById("no").value;
          var newpass=document.getelementById("pass").value;
          alert("you entered new username"+newuser);
          alert("you entered new password"+newpass);
       }   

我想更改占位符值 onclick 事件，并再次使用相同的按钮单击和我想要获取输入数据的方法。我附上了我的代码，但它不起作用。

Answer 1

这两行中的 getElementById 拼写错误。除此之外，代码对我来说似乎运行良好。

var newuser = document.getElementById("no").value;
var newpass = document.getElementById("pass").value;

var entry = 0;

function change() {

  if (entry == 0) {
    document.getElementById("no").placeholder = "Enter user name...";
    document.getElementById("pass").placeholder = "Enter user password";
    entry++;
  } else {
    var newuser = document.getElementById("no").value;
    var newpass = document.getElementById("pass").value;
    alert("you entered new username: " + newuser);
    alert("you entered new password: " + newpass);
  }
}

<div id="abc" class="first">
<input type="text" placeholder="Number" id="no" class="contact">
<input type="text" placeholder="Pass" id="pass" class="password">
<div class="btn1" role="group">
  <button type="button" onclick="change()" class="btnregi">Register 
        </button>
</div>