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With the rapid development of mobile Internet, users have higher and higher requirements for page interactivity and user experience. The functions of expanding and collapsing text are becoming more and more common in page design, which can improve the readability and aesthetics of the page. This article will introduce how to implement the functions of expanding and collapsing text in Vue.

1. Demand Analysis

Before implementing the text expansion and collapse function, we need to analyze the requirements. For the text expansion and collapse function, we need to consider the following aspects:

1. When the text length exceeds a certain range, an expand/collapse button needs to be displayed.
2. In the initial state, only text of a certain length is displayed. Click the expand button to display all the text, and click the collapse button again to hide the redundant text.
3. The expanded/collapsed state needs to be saved, that is, the last state should be maintained when the user opens the page again.

2. Implementation ideas

Based on the demand analysis, we can come up with the implementation ideas:

1. Use v-ifthe command to determine whether the text length exceeds a certain range. If so, display the expand/collapse button.
2. Use v-showthe command to control the display and hiding of text. In the initial state, only text of a certain length is displayed. Click the expand button to display all the text, and click the collapse button again to hide the extra text.
3. Use Vuethe lifecycle hook functions mounted and updated to save the expanded/collapsed state.

3. Implementation steps

Use the directive in the template v-ifto determine whether the text length exceeds a certain range. If so, display the expand/collapse button.

<template>
  <div>
    <p v-if="showBtn">{{ content }}</p>
    <button v-if="showBtn" @click="toggleContent">
      {{ isCollapsed ? '展开' : '收起' }}
    </button>
  </div>
</template>

Define variables in data to save the expanded/collapsed state of the text. Update the state in the mounted and updated lifecycle hook functions.

<script>
export default {
  data() {
    return {
      content: '这是一段很长的文字，需要展开和收起。',
      maxLength: 20,
      isCollapsed: true,
      showBtn: false,
    };
  },
  mounted() {
    this.showBtn = this.content.length > this.maxLength;
  },
  updated() {
    this.showBtn = this.content.length > this.maxLength;
  },
  methods: {
    toggleContent() {
      this.isCollapsed = !this.isCollapsed;
    },
  },
};
</script>

Use v-showthe command to control the display and hiding of text.

<template>
  <div>
    <p v-if="showBtn" v-show="isCollapsed">{{ content.substring(0, maxLength) }}...</p>
    <p v-if="showBtn" v-show="!isCollapsed">{{ content }}</p>
    <button v-if="showBtn" @click="toggleContent">
      {{ isCollapsed ? '展开' : '收起' }}
    </button>
  </div>
</template>

4. Example Demonstration

Here is a complete example code, which can be viewed on CodePen.

<template>
  <div>
    <p v-if="showBtn" v-show="isCollapsed">{{ content.substring(0, maxLength) }}...</p>
    <p v-if="showBtn" v-show="!isCollapsed">{{ content }}</p>
    <button v-if="showBtn" @click="toggleContent">
      {{ isCollapsed ? '展开' : '收起' }}
    </button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      content: '这是一段很长的文字，需要展开和收起。',
      maxLength: 20,
      isCollapsed: true,
      showBtn: false,
    };
  },
  mounted() {
    this.showBtn = this.content.length > this.maxLength;
  },
  updated() {
    this.showBtn = this.content.length > this.maxLength;
  },
  methods: {
    toggleContent() {
      this.isCollapsed = !this.isCollapsed;
    },
  },
};
</script>

V. Conclusion

The function of expanding and collapsing text can improve the readability and aesthetics of the page, and is one of the common functions in page design. To implement the function of expanding and collapsing text in Vue, we need to analyze the requirements first, and then come up with implementation ideas based on the requirements analysis. Finally, we can use v-ifthe directive to determine whether the length of the text exceeds a certain range, use v-showthe directive to control the display and hiding of the text, and use Vue's life cycle hook functions mounted and updated to save the expansion/collapse status.