How to achieve ceiling effect in vue

Preface

In web applications, we often need to keep one or more elements in the page in a fixed position when the page is scrolled. This effect is often called a ceiling effect because it makes the element stay in place as if it were glued to the top of the page.

In Vue, there are different ways to achieve the ceiling effect. This article describes one of these methods and provides sample code.

Method

The method to achieve the ceiling effect in Vue is to listen to page scroll events, calculate the positional relationship between the current scroll position and the ceiling element, and dynamically add or remove CSS styles. accomplish.

The specific steps are as follows:

1. Define a variable to mark whether the ceiling element should be fixed at the top of the page. For example, in the following example, we use a variable called isFixed.

data() {
  return {
    isFixed: false
  }
},

2. In the mounted hook function, add a page scroll event listener.

mounted() {
  window.addEventListener('scroll', this.handleScroll)
},

3. Define the function handleScroll that handles scroll events in methods, and calculate the distance between the current scroll position and the ceiling element in this function Positional relationship.

methods: {
  handleScroll() {
    const scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop
    const testEle = this.$refs.test
    if (scrollTop > testEle.offsetTop) {
      this.isFixed = true
    } else {
      this.isFixed = false
    }
  }
},

In the above code, we obtain the scroll position of the current page and the position of the ceiling element (use $refs to obtain the reference of the element). Then, we set the value of the isFixed variable based on the positional relationship between the current scroll position and the ceiling element.

4. In the class attribute of the ceiling element, dynamically bind a fixed class name. The appearance of the class name depends on isFixed The value of the variable.

<div ref="test" :class="{fixed: isFixed}">
  // 吸顶元素的内容
</div>

Complete code

The following is a simple example showing how to use Vue to achieve a ceiling effect.

<template>
  <div>
    <div class="header">
      // 头部元素的内容
    </div>
    <div ref="test" :class="{fixed: isFixed}">
      // 吸顶元素的内容
    </div>
    <div class="content">
      // 页面内容
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isFixed: false
    }
  },
  mounted() {
    window.addEventListener('scroll', this.handleScroll)
  },
  methods: {
    handleScroll() {
      const scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop
      const testEle = this.$refs.test
      if (scrollTop > testEle.offsetTop) {
        this.isFixed = true
      } else {
        this.isFixed = false
      }
    }
  }
}
</script>

<style>
.fixed {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 99;
}
.header {
  height: 100px;
  background-color: #eee;
}
.content {
  height: 2000px;
}
</style>

In the above code snippet, we use the fixed class name to control the fixed position of the ceiling element and set some simple CSS styles.

Conclusion

It is very simple to implement the ceiling effect in Vue. You only need to listen to the page scroll event, calculate the position relationship, and set the style. Whether in actual work or in the process of practicing Vue knowledge, the ceiling effect is a very useful technique. I hope this article can be helpful to everyone.

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