Question

我只想删除包含if条件的属性，然后将其添加回else。

function onFocusChange () { 
  if (document.getElementById("input").focus()) { 
     document.getElementById("input").placeholder = "";
   else { 
     document.getElementById("input").placeholder = "This is Placeholder Text";   
   }
  }
}

加价：

<label for="input">
  Question #1:
</label>
<input type="text" id="input" name="Address" required="required" placeholder="This is Placeholder Text" />

Answer 1

要删除属性，您可以使用element.removeAttribute("placeholder");

Answer 2

您可以使用focus＆amp; blur事件

＆＃13;

var element = document.getElementById('input');
element.addEventListener('focus', function() {
  element.setAttribute('placeholder', '')

})

element.addEventListener('blur', function() {
  element.setAttribute('placeholder', 'This is Placeholder Text')

})

＆＃13;

<label for="input">
  Question #1:
</label>
<input type="text" id="input" name="Address" required="required" placeholder="This is Placeholder Text" />

＆＃13;

在plain JS（非jQuery）中删除焦点上的占位符属性

2 个答案: