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With the development of mobile Internet, users have higher and higher requirements for page experience, one of which is the display method of long text. In some mobile applications, in order to avoid the page being too long, it is often necessary to expand and collapse the long text to improve the user experience. This article will introduce how to expand and collapse text in Vue.

1. Demand Analysis

The function we need to implement is: when the user clicks the "Expand" button, the text content is fully displayed; when the user clicks the "Collapse" button, the text content is collapsed again. At the same time, when the text content is long, part of the content needs to be omitted and "..." is displayed so that the user knows that there is more content to expand.

2. Implementation Method

In Vue, we can use the v-if and v-show instructions to expand and collapse text.

1. v-if

The v-if directive is used to switch the existence of an element based on the truth of the expression. When the value is true, the element exists; when the value is false, the element does not exist. We can control the value of v-if through a variable in data to achieve the effect of expansion and collapse. The sample code is as follows:

<template>
  <div>
    <p v-if="isShow">{{ text }}</p>
    <button v-if="!isShow" @click="toggleShow">展开</button>
    <button v-if="isShow" @click="toggleShow">收起</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isShow: false,
      text: '这是一段很长的文本内容，需要进行展开与收起的操作。',
    };
  },
  methods: {
    toggleShow() {
      this.isShow = !this.isShow;
    },
  },
};
</script>

2. v-show

The v-show directive is used to switch the display and hiding of an element based on the truth of the expression value. When the value is true, the element is displayed; when the value is false, the element is hidden. Unlike v-if, v-show does not destroy and rebuild the element when switching, but achieves it by modifying the display style of the element. We can also control the value of v-show through a variable in data to achieve the effect of expansion and collapse. The sample code is as follows:

<template>
  <div>
    <p v-show="isShow">{{ text }}</p>
    <button v-show="!isShow" @click="toggleShow">展开</button>
    <button v-show="isShow" @click="toggleShow">收起</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isShow: false,
      text: '这是一段很长的文本内容，需要进行展开与收起的操作。',
    };
  },
  methods: {
    toggleShow() {
      this.isShow = !this.isShow;
    },
  },
};
</script>

3. Notes

1. You need to truncate the text and add an ellipsis (…) so that the user knows there is more content to expand. You can use the CSS text-overflow property to achieve this.
2. The button needs to be styled so that users can clearly know what the button does.
3. In the implementation process, you need to pay attention to the difference between v-if and v-show. v-if will destroy and rebuild elements when switching, while v-show will not. Therefore, in the case of frequent switching, using v-show can improve performance.
4. During the implementation process, you need to pay attention to the naming of variables to ensure the readability and maintainability of the code.

In short, it is not difficult to expand and collapse text in Vue. You just need to master the use of the two instructions v-if and v-show, and pay attention to some details. By using these instructions reasonably, we can greatly improve the user experience and make the page more beautiful and easy to use.