为什么提交时会触发事件？

Question

在注册中，我想让用户点击进入后电子邮件就自动消失。我已经添加了JS来隐藏和取消隐藏占位符文本。

代码：

<form id="form" action="https://xxxx.com/subscribe/post-json?u=xxx&id=xx&c=?" method="GET">
  <input type="hidden" name="u" value="xxx">
  <input type="hidden" name="id" value="xxx">
  <input id="email" type="EMAIL" autocapitalize="off" autocorrect="off" name="MERGE0" id="MERGE0" size="25" placeholder= "Type your email and press enter">
  <p id="response"></p>
</form>

JS代码：

<script >

 var text = document.getElementById("email");  

    text.onfocus = function() {
        if ( text.placeholder == "Type your email and press enter") {
            text.placeholder = "";
        }      
    };    
    text.onblur = function() {
        if ( text.placeholder == "") {
            text.placeholder = "Type your email and press enter";
        }
    };
</script>

我试图创建一个函数来触发该事件，但它不起作用：

 function checkEnter(event)
{
   if (event.keyCode == 13) {text.placeholder = "cool";}
};

你们能发现我的代码出了什么问题吗？

Answer 1

You need to add a event listener for the enter key. You could remove your function checkEnter and use this instead:

document.querySelector('#email').addEventListener('keypress', function (e) {
  var key = e.which || e.keyCode;
  if (key == 13) {
    text.placeholder = "cool";
  }
};