使用JS获取正确的占位符颜色

Question

我将输入的默认占位符颜色更改为蓝色.为什么我用Javascript获得黑色占位符颜色？

const getPlaceholderColor = () => {
  let inputEl = document.querySelector('.myClass');
  let inputElStyle = window.getComputedStyle(inputEl, '::placeholder');
  
  let resultTarget = document.getElementById('colorResult');
  let placeholderColor = inputElStyle.getPropertyValue('color');
  resultTarget.innerHTML = `Placeholder color: ${placeholderColor}`;
}

.myClass::placeholder {
  color: #004085;
}

.marginTop20 {
  margin-top: 20px;
}

<input
  type="text"
  placeholder="Enter name"
  class="myClass"
/>

<button onClick="getPlaceholderColor()">Get placeholder color</button>

<div class="marginTop20" id="colorResult"></div>

Answer 1

问题写在这里=> https://css-tricks.com/almanac/selectors/p/placeholder/

下面是一个使用 :placeholder-shown 和 ::placeholder 的代码笔

https://codepen.io/kipomaha/pen/pOOdQr

document.getElementById("myStyles").sheet.insertRule('.myClass:placeholder-shown { color: red; }');
document.getElementById("myStyles").sheet.insertRule('.myClass::placeholder { color: red; }');
const getPlaceholderColor = () => {
    let inputEl = document.querySelector('.myClass');
    let inputElStyle = window.getComputedStyle(inputEl, ':placeholder-shown');
    let resultTarget = document.getElementById('colorResult');
    let placeholderColor = inputElStyle.getPropertyValue('color');

    resultTarget.innerHTML = `Placeholder color: ${placeholderColor}`;
}


document.getElementById("myStyles").sheet.insertRule('.myClass:placeholder-shown { color: red; }');
document.getElementById("myStyles").sheet.insertRule('.myClass::placeholder { color: red; }');

var inputEl = document.querySelector('.myClass'); 
var placeholderColor = inputElStyle.getPropertyValue('color');
const getPlaceholderColor = () => {
    let inputElStyle = window.getComputedStyle(inputEl, ':placeholder-shown');
    let resultTarget = document.getElementById('colorResult');

    resultTarget.innerHTML = `Placeholder color: ${placeholderColor}`;
}