更改文本背景荧光笔

Question

因此，我试图让我的id="highlighter2"的每行背景颜色 在单击时具有黄色背景，因此看起来与此类似/ p>

并在单击时将按钮替换为“全部取消突出显示” 按钮，从而取消突出显示所有内容。我尝试用ID定义onclick，但改为更改背景，这是正确的方法？

代码：

function Highlighter() {
  var p = document.getElementById("poem"); // get the paragraph
  var p = document.getElementById("highlighter2");
  document.body.style.backgroundColor = "yellow";
}

#poem {
  padding: 10px;
  margin-bottom: 10px;
  color: blue;
  font-size: 1.25em;
  font-family: sans-serif;
  background-color: silver;
  border: 1px dashed black;
  width: 70%;
}

<div id="poem">
  <h2> How Many, How Much </h2>
  <h4> by Shel Silverstein </h4>

  <p id="highlighter2">
    <p> How many slams in an old screen door? </p>
    <p> Depends how loud you shut it.</p>
    <p> How many slices in a bread?</p>
    <p> Depends how thin you cut it.</p>
    <p> How much good inside a day? </p>
    <p> Depends how good you live 'em. </p>
    <p> How much love inside a friend? </p>
    <p> Depends how much you give 'em. </p>
  </p>


</div>

<button type="button" onclick="Highlighter()">Click to highlight</button>
<!-- Highlight -->

Answer 1

Paragraphs: the P element

  

P元素代表一个段落。它不能包含块级元素（包括P本身）。

因此，请使用其他元素来包装所有p元素，例如div。

您可以根据按钮的文本更改背景颜色和文本。

要分别设置所有backgroundColor元素的p，您必须首先定位所有元素。您可以使用querySelectorAll()来做到这一点。然后按照以下方式在 NodeList 上使用forEach()：

function Highlighter(btn) {
  var p = document.querySelectorAll('#highlighter2 > p'); // get the paragraph
  if(btn.textContent == 'Click to highlight'){
    p.forEach(function(pEl){
      pEl.style.backgroundColor = "yellow";
    }); 
    btn.textContent = 'Unhighlight them all';
  }
  else{
    p.forEach(function(pEl){
      pEl.style.backgroundColor = "";
    });
    btn.textContent = 'Click to highlight';
  }
}

#poem {
  padding: 10px;
  margin-bottom: 10px;
  color: blue;
  font-size: 1.25em;
  font-family: sans-serif;
  background-color: silver;
  border: 1px dashed black;
  width: 70%;
}

<div id="poem">
  <h2> How Many, How Much  </h2>
  <h4> by Shel Silverstein </h4>

  <div id="highlighter2">
    <p> How many slams in an old screen door? </p>
    <p> Depends how loud you shut it.</p>
    <p> How many slices in a bread?</p>
    <p> Depends how thin you cut it.</p>
    <p> How much good inside a day? </p>
    <p> Depends how good you live 'em. </p>
    <p> How much love inside a friend? </p>
    <p> Depends how much you give 'em. </p>
  </div>


</div>

<button type="button" onclick="Highlighter(this)">Click to highlight</button><!-- Highlight -->

Answer 2

document.body.style.backgroundColor将您的风格应用于身体。试试这个document.getElementById("highlighter2").style.backgroundColor

或document.p.style.backgroundColor