如何在我的 vuejs 组件中嵌入 javascript 代码？

Question

I'm new in frontend developement, I'm using Vue.js and I want to create a sticky navbar. I found this method but I didn't find how to embed this JavaScript code in my .vue file.

window.onscroll = function() {myFunction()};

var navbar = document.getElementById("navbar");
var sticky = navbar.offsetTop;

function myFunction() {
  if (window.pageYOffset >= sticky) {
    navbar.classList.add("sticky")
  } else {
    navbar.classList.remove("sticky");
  }
}

I've dropped the navbar and sticky variables in data and the function in the methods but it won't work.

<script>
window.onscroll = function() {myFunction()};

export default {
  name: "About",
  data() {
    return {
      navbar : document.getElementById("navbar"),
      sticky : navbar.offsetTop

    }},
    methods: {
       handleScroll (event) {
         if (window.pageYOffset >= sticky) {
    navbar.classList.add("sticky")
  } else {
    navbar.classList.remove("sticky");
  }

    }}
<script>

---

EDIT:

I've just done it and the whole page is blank now

here is the whole .vue file

<template> <div class="about"> <div class="header"> <h2>Scroll Down</h2> <p>Scroll down to see the sticky effect.</p> </div> <div id="navbar"> <a class="active" href="javascript:void(0)">Home</a> <a href="javascript:void(0)">News</a> <a href="javascript:void(0)">Contact</a> </div> <div class="content"> <h3>Sticky Navigation Example</h3> <p>The navbar will stick to the top when you reach its scroll position.</p> <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p> <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p> <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p> <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p> <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p> <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p> <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p> </div> </div> </template> <script> window.addEventListener('scroll', this.onScroll); export default { name: "About", data() { return { navbar : document.getElementById("navbar"), sticky : navbar.offsetTop }}, methods: { onScroll () { if (window.pageYOffset >= sticky) { navbar.classList.add("sticky") } else { navbar.classList.remove("sticky"); } } // Any code to be executed when the window is scrolled }} </script> <style scoped> body { margin: 0; font-size: 28px; font-family: Arial, Helvetica, sans-serif; } .header { background-color: #f1f1f1; padding: 30px; text-align: center; } #navbar { overflow: hidden; background-color: #333; } #navbar a { float: left; display: block; color: #f2f2f2; text-align: center; padding: 14px 16px; text-decoration: none; font-size: 17px; } #navbar a:hover { background-color: #ddd; color: black; } #navbar a.active { background-color: #4CAF50; color: white; } .content { padding: 16px; } .sticky { position: fixed; top: 0; width: 100%; } .sticky + .content { padding-top: 60px; } </style>

Answer 1

You could try something like this:

<script>
export default {
    data: {},
      mounted: function() {
        window.addEventListener('scroll', this.scrollHandle)
      },
      methods: {
          scrollHandle() {
              var navbar = document.getElementById("navbar");
              var sticky = navbar.offsetTop;

              if (window.pageYOffset >= sticky) {
                  navbar.classList.add("sticky")
              } else {
                    navbar.classList.remove("sticky");
              }
          },
      }
}
</script>

You set your event handler in the mounted function so it'll be run before the component is loaded entirely. This way you'll get your scrolling where you need like in the vanilla js example.

Although this will work you should try to avoid manipulating the DOM since VUE uses VirtualDOM . It's a good habit to get into as it's consider better practice, and you'll find it make maintenance down the road much easier should you need to revisit your component later on.

As an alternative to using JS and DOM manipulation you can look into using CSS position:sticky for a css approach, instead of handling that with javascript. Something like this would do the trick from CSS:

<template>
    ...
    <div id="nav" class="sticky">
       ...
    </div>
    ...
</template>
<style>
...
.sticky {
    position: sticky;
    top: 0em;
}
...
<style>

Answer 2

I've just done it and the whole page is blank now

here is the whole .vue file

<template>
  <div class="about">
    <div class="header">
      <h2>Scroll Down</h2>
      <p>Scroll down to see the sticky effect.</p>
    </div>

    <div id="navbar">
      <a class="active" href="javascript:void(0)">Home</a>
      <a href="javascript:void(0)">News</a>
      <a href="javascript:void(0)">Contact</a>
    </div>

    <div class="content">
      <h3>Sticky Navigation Example</h3>
      <p>The navbar will stick to the top when you reach its scroll position.</p>
      <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p>
      <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p>
      <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p>
      <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p>
      <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p>
      <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p>
      <p>Some text to enable scrolling.. Lorem ipsum dolor sit amet, illum definitiones no quo, maluisset concludaturque et eum, altera fabulas ut quo. Atqui causae gloriatur ius te, id agam omnis evertitur eum. Affert laboramus repudiandae nec et. Inciderint efficiantur his ad. Eum no molestiae voluptatibus.</p>
    </div>
  </div>
</template>

<script>
window.addEventListener('scroll', this.onScroll);

export default {
  name: "About",
  data() {
    return {
      navbar : document.getElementById("navbar"),
      sticky : navbar.offsetTop

    }},
    methods: {
       onScroll () {
         if (window.pageYOffset >= sticky) {
    navbar.classList.add("sticky")
  } 
  else {
    navbar.classList.remove("sticky");
  }

    }
      // Any code to be executed when the window is scrolled

  }}


</script>

<style scoped>
  body {
  margin: 0;
  font-size: 28px;
  font-family: Arial, Helvetica, sans-serif;
}

.header {
  background-color: #f1f1f1;
  padding: 30px;
  text-align: center;
}

#navbar {
  overflow: hidden;
  background-color: #333;
}

#navbar a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}

#navbar a:hover {
  background-color: #ddd;
  color: black;
}

#navbar a.active {
  background-color: #4CAF50;
  color: white;
}

.content {
  padding: 16px;
}

.sticky {
  position: fixed;
  top: 0;
  width: 100%;
}

.sticky + .content {
  padding-top: 60px;
}
</style>