Javascript implements expansion and collapse of a piece of text

<p>JavaScript implements the expand and collapse function of a paragraph of text

<p>As web design pays more and more attention to user experience, more and more page designs will need to expand or collapse a paragraph of text. This Sometimes we can use JavaScript code to achieve this function. Let's take a look at how to use JavaScript to expand and collapse a piece of text.

1. HTML code

<p>First, we need to prepare a piece of HTML code. This code can be the text that needs to be expanded and collapsed and the rest of the page elements. The sample code is as follows:

<div class="content">
  <p>这是一段需要展开收起的文字，可以有很多很多的字，可能会占据很多的空间。因此，在默认情况下，我们只会显示部分文字，而把其余的部分折叠起来。如果需要查看全部内容，可以点击“查看更多”按钮，文字内容就会展开显示了。</p>
  <button class="btn-more">查看更多</button>
</div>

<p>In this code, we use a <div> tag to wrap the text and button elements that need to be expanded and collapsed. In the <div> tag, we use a <p> tag to display the text content that needs to be expanded and collapsed. Below the text content, use a &lt ;button> tag to display the "See more" button.

2. CSS Style

<p>We need to use CSS to set the style of the text that needs to be expanded and collapsed in the default and expanded states.

.content p {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  /* 设置文字溢出时显示省略号 */
}

.content p.is-expanded {
  overflow: visible;
  white-space: normal;
  /* 文字溢出时不再显示省略号 */
}

.btn-more {
  display: block;
  margin-top: 10px;
  cursor: pointer;
  /* 设置鼠标指针为手型 */
}

3. JavaScript code

<p>Next, we need to use JavaScript code to implement the click event of the "View More" button so that it can be expanded or collapsed when the button is clicked Text that needs to be expanded or collapsed.

<p>First, we can create a variable to store whether it is currently in the expanded state. The initial state is false, which means it is in the collapsed state.

let isExpanded = false;

<p>When the user clicks the "View More" button, we need to get the <p> element that needs to expand and collapse the text, and add or remove a # for this element. ##is-expanded's class. At the same time, change the text content of the button to display "Less" or "View More" to remind the user of the current text status.

const content = document.querySelector('.content');
const btnMore = document.querySelector('.btn-more');

btnMore.addEventListener('click', function() {
  const paragraph = content.querySelector('p');
  isExpanded = !isExpanded;
  
  if (isExpanded) {
    paragraph.classList.add('is-expanded');
    btnMore.innerText = '收起';
  } else {
    paragraph.classList.remove('is-expanded');
    btnMore.innerText = '查看更多';
  }
});

In this code, we first use the <p>document.querySelector() method to obtain the <p> elements corresponding to the text that needs to be expanded and collapsed. The element corresponding to the "View More" button. Then, add a click event listener to the button element, which will fire when the user clicks the button.

In the event listener, we will use the status of the <p>isExpanded variable to determine whether the current text is expanded or collapsed. If it is in the expanded state, we will add a class is-expanded to the <p> element and set the button's text to "Collapse". Instead, we will remove the is-expanded class and set the button's text to "See more".

So far, we have successfully implemented the expand and collapse function of a paragraph of text. When the user clicks the "View More" button, the text that needs to be expanded or collapsed can be expanded or collapsed, making the page more concise and easier to read. <p>

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